Upon settling down at Khaybar, the Banu Nadhir decided to seek revenge against the Muslims. They contacted the Meccans, and 20 leaders from the Jews and 50 from the Quraish made covenant in the Ka'bah that so long as they lived, they would fight Muhammad. Then the Jews and the Quraish contacted their allies and sent emissaries to a number of tribes. Banu Ghatfan, Banu Asad, Banu Aslam, Banu Ashja', Banu Kinanah and Banu Fizarah readily responded and the coalition contributed ten thousand soldiers who marched upon Medina under the command of Abu Sufyan.

When news of these preparations reached Medina, the Holy Prophet consulted his companions. Salman al-Farsi advised to dig a moat on the unprotected side of Medina.

Muslims were divided into parties of 10, and each party was allotted 10 yards to dig. The Holy Prophet himself participated in this task. The khandaq (moat) was completed in nick of time: just 3 days before the host of the enemies reached Medina. The Muslims could muster only three thousand men to face this huge army.

Huyaiy ibn Akhtab, head of Banu Nadhir, met secretly with Ka'b ibn Asad, head of Banu Quraizah, a Jewish tribe still in Medina. Banu Quraizah, on his instigation, tore down the treaty, which they had concluded with the Muslims.

This treachery and danger from inside Medina, when Muslims were surrounded by the combined armies of pagans and Jews of all of Arabia on the outside, had a telling effect on the Muslims. As a meager safeguard, Salimah ibn Aslam was deputed with only two hundred men to guard the city from any attack by Banu Quraizah. The enemy was astonished to see the moat because it was a new thing for the Arabs. They camped on the outside for 27 (or 24) days. Their number increased day by day, and many Muslims were extremely terrified, as the Qur'an gives us the picture. Surah al-Ahzab describes various aspects of this siege. For example, see the following verses:

When they came upon you from above you and from below you, and when the eyes turned dull, and the hearts rose up to the throats, you began to think diverse thoughts about Allah. There, the believers were tried, and they were shaken a tremendous shaking. (Qur'an, 33:10-11)

At that time, many hypocrites, and even some Muslims, asked permission to leave the rank of the Muslims and to return to their homes:

And when a party of them said: O people of Yathrib! There is no place for you to stand, and a party of them asked permission of the Prophet saying: Verily our houses are exposed, and they were not exposed; they only desired to fee away. (Qur'an, 33:13)

The bulk of the army, however, steadfastly bore up the hardship of inclement weather and rapidly depleting provisions. The coalition's army hurled arrows and stones at the Muslims.

Finally, a few of the Quraish's more valiant warriors, 'Amr ibn 'Abdwadd, Nawfil ibn 'Abdullah ibn Mughirah, Dhirar ibn Khattab, Hubairah ibn Abi Wahab, 'Ikrimah ibn Abi Jahl and Mirdas al-Fahri, succeeded in crossing the moat.

'Amr called for battle; nobody responded; he was considered equal to one thousand warriors. History accounts state that all the Muslims were as though birds were sitting on their heads: they were too afraid to raise their heads.

Three times did the Holy Prophet exhort the Muslims to give battle to Amr. Three times it was only 'Ali who stood up. In the third time, the Holy Prophet allowed 'Ali to go. When 'Ali was going to the battlefield, the Holy Prophet said:

"The whole faith is going to fight the whole infidelity."

'Ali invited 'Amr to accept Islam, or to return to Mecca, or to come down from his horse since 'Ali had no horse and was on foot. 'Amr alighted from his horse and a fierce battle ensued. For a while, so much dust covered both warriors that nobody knew what was going on. Once 'Amr succeeded in inflicting a serious cut on 'Ali's head, yet after some time, 'Ali killed 'Amr. Concerning this battle, the Holy Prophet said:

"Verily, one attack of 'Ali in the Battle of Khandaq is better than the worship of all human beings and jinns, up to the Day of Resurrection."

This killing of 'Amr demoralized the pagans, and all his companions fled away except Nawfil, who was also killed by'Ali.

The Muslims were short of provisions. The Holy Prophet had to tie a stone on his stomach in order to lessen the pangs of hunger. Abu Sa'eed al-Khudri said: "Our hearts had reached our throats in fear and desperation." On the other hand, the besieging army was getting restive; it could not put up any further with the rain and cold; its horses were perishing and provisions nearing exhaustion.
The Holy Prophet went to the place where the Mosque of Victory (Masjid-ul-Fath) now stands and prayed to Allah. A fierce storm raged which uprooted the tents of the enemies; their pots and belongings went flying in all directions; an unbearable terror was cast in their ranks. The Meccans and the pagan tribes fled away. The first to flee was Abu Sufyan himself who was so upset that he tried to ride his camel without first untying its rope. This episode is referred to in the Qur'an in this ayat:

O ye who believe! Remember the bounty of Allah unto you when came upon you the hosts, so We sent against them a strong wind and hosts that ye saw not: and Allah is seeing all what you do (Qur'an, 33:9)

And also in ayat 25 which says:

And God turned back the unbelievers in their rage; they did not achieve any advantage, and Allah sufficed for the believers infighting, and
Allah is Strong, Mighty. (Qur'an, 33:25)

'Abdullah ibn Mas'ud was interpreting this ayat in (Tafsir ad-Durrul-Manthur) thus:

"And God sufficed the believers (through 'Ali ibn Abi Talib) in their fight"

As a direct result of this defeat of the infidels' combined forces in the Battle of Ahzab, the influence of the Quraish waned, and those, tribes who were till then hesitating to accept Islam out of their fear of Quraish began to send deputations to the Prophet. The first deputation came from the tribe of Mazinah, and it consisted of four hundred persons. They not only accepted Islam but also were ready to settle down at Medina. The Prophet advised them to return to their homes.

Likewise, a deputation of a hundred persons came from the Ashja' and embraced Islam. The tribes of Juhainah lived near them and were influenced by their conversion. One thousand of their men came to Medina and entered the fraternity.

Elimination of the Bann Quraizah
According to the terms of the treaty which the Banu Quraizah had contracted with the Muslims, they were bound to assist the Muslims against outside aggression. But, not to speak of assisting the Muslims or even remaining neutral, they had sided with the Meccans and joined the besieging foe. What was worse, they had tried to -attack the fortress where Muslim women and children had been lodged for safety. Living in such a close proximity to Medina, they had become a serious menace.
As soon as the siege of their own town was lifted, the Muslims surrounded the Banu Quraizah's fortress. For some time they resisted but they ultimately opened the gates of their fortresses on the condition that their fate should be decided by Sa'd ibn Ma'adh, chief of the Aws. Basing his judgement upon the direction contained in the Old Testament itself, Sa'd ruled that the fighting men should be killed and their women and children made captive. The sentence was carried out. It was in this connection that the following ayats were revealed:

And He drove down those of the people of the Book who backed them from their fortresses, and He cast awe into their hearts: some you killed and you took captive another part (of them). And He made you inherit their land and their dwellings and their properties, and (to) a land which ye have not yet trodden, and God has power over all things. (Qur'an, 33:26-27)

Many critics had described this punishment as harsh. But what other punishment could be meted out to them? They had violated the pact and, instead of helping the Muslims, they joined the forces of their enemies and had actually besieged the Muslims. There were no prisons where prisoners of war could be detained nor any concentration camps where they could be put to forced labor, and the capture of women and children, thoughk appaling to the notions of the present age, was probably the only method known in those days to provide sustenance to them when the earning members of their families had lost their lives. At any rate, this was the customary aftermath of a war.
The Treaty of Hudaibiah and the Pledge of Ridhwan
In Dhul-Qa'dah, 6 A.H., the Prophet decided to perform the 'umrah (the lesser pilgrimage) to the Ka'bah which had been till then denied to the Muslims due to the hostility of the Meccans. Fourteen hundred Muhajirun and Ansar showed readiness to go with him. Lest there be any misgivings in any quarter about his intentions, he directed the Muslims not to carry any arms other than swords, and he himself put on the robes of ihram and took up camels to sacrifice.
The Muslims camped at Hudaibiyah, ten miles from Mecca. An envoy was sent to the Meccans to obtain-their permission for visiting the Ka'bah but it was rejected. Instead, the Meccans collected a force to prevent the Muslims from entering Mecca. The Quraish sent Budayl of the tribe of Khuza'ah, to tell the Prophet that he was not allowed to visit the Ka'bah. The Prophet said that he had not gone there to fight but to perform the pilgrimage.

The Quraish deputed 'Urwah ibn Mas'ud al-Thaqafi to have a talk with the Prophet, but nothing came out of it. The Prophet then sent Karash ibn Umayyah to the Quraish, but the messenger was mistreated, and it was only with difficulty that he escaped with his life. The vanguard of the Quraish attacked the Muslims, but it was captured. The Prophet demonstrated great clemency and set the captives free. Ultimately, 'Uthman (who belonged to the same clan to which Abu Sufyan belonged) was sent to persuade the Quraish to allow the Muslims to visit the Ka'bah. News came that 'Uthman had been killed by the Quraish. The Muslims took a pledge on the hands of the Prophet, known as "Bay'atur-Ridhwan", to stand by him to the last. Referring to this pledge, the Qu'ran says:

Indeed God was well pleased with the believers when they swore allegiance to thee under the tree, and He knew what was in their hearts, so He sent down tranquility on them and rewarded them with a near victory. (Qur'an, 48:18)

However, it came to be known later that the news of Uthman's murder was not true. After considerable difficulty, a treaty was ultimately signed with Suhayl ibn 'Amr, Quraish's envoy, on the following terms reproduced in almost all the Arab Chronicles:

• The Muslims should return to Medina that year without performing the pilgrimage.

• They could return the next year but their stay should not exceed three days.

• The Muslims should not bring any arms with them except sheathed swords.

• There would be no war between the Quraish and the Muslims for ten years.

• Muslims residing in Mecca would not be allowed to migrate to Medina, but if any Muslim wanted to settle in Mecca, he should not be prevented from doing so.

• Any idolater or Meccan Muslim migrating to Medina without the permission of his clan will be sent back to Mecca, but a Muslim of Medina going back to Mecca without permission will not be allowed to return.

• Any tribe in Arabia will be free to join any of the parties to the pact, and the allies also will be bound by this treaty.

Although these terms were apparently disadvantageous to the Muslims, the Prophet accepted them. No sooner had the terms been agreed upon than a critical situation arose. Abu Jundal, son of the said Suhail, had been imprisoned by his father for accepting Islam and was being severely mistreated. He managed to escape and, with his fetters on, reached Hudaibiyah just before the treaty was signed. Suhail, the emissary of the Meccans, demanded his return according to the terms of the treaty.
The Muslims said that the treaty had not been signed yet. Suhail said that if his son was not returned to him, there would be no treaty at all. Abu Jundal pleaded with the Muslims in the name of mercy not to throw him back to the tyranny of the Meccans and showed the injuries they had inflicted upon him. The Muslims were moved to plead his cause and 'Umar made an impassioned appeal, but the Prophet silenced them by declaring that he could not break a treaty. He consoled Abu Jundal by saying that God would create some way for his deliverance.

Some Muslims were unhappy abut this treaty. 'Umar ibn al-Khattab talked very rudely to the Holy Prophet. Afterwards, he used to say: "Never did I have doubt (about the truth of Islam) since my acceptance of Islam except on that day (of Hudaibiyah)."

The Prophet sacrificed his animals at Hudaybiyah. Having shaved his head, he removed the robes of ihram. Many Muslims were reluctant to do so, but finally they followed suit.

After three days' stay at Hudaibiyah, the Muslims returned to Medina. On the way back, Surah 48 titled "TheVictory" was revealed. It described the treaty as an open victory for the Muslims. Later events confirmed that it was really a great victory for them.

Till then, idolaters and Muslims had not been mixing with each other. By virtue of this treaty, they started doing so freely. On account of their family relationships and trade connections, the Meccans started visiting Medina, and many of them stayed there for months. In this way, they were getting acquainted with the teachings of Islam and were deeply impressed by the righteous conduct and moral integrity of the Muslims.
The Muslims of Medina who were visiting Mecca left behind them similar impressions. The result was that the Meccans were themselves attracted to Islam and many of them embraced the new religion. It is recorded that during the two years following this treaty, more people accepted Islam than during the whole nineteen years since the inception of the mission. A clear proof is found in the fact that while only 1,400 Muslims had accompanied the Prophet for the lesser pilgrimage when the treaty of Hudaibiyah was concluded, two years later, that is, when Mecca fell in the hands of the Muslims, 10,000 Muslims accompanied him.

Inviting Sovereigns of Neighboring States
The tranquility afforded by the Hudaibiyah peace treaty gave an opportunity to the Prophet to propagate Islam throughout Arabia and to enable Islam to embark upon its attempt to embrace all humanity. He sent ambassadors with his letters to Heraclius, the Byzantine emperor, to Khusro Parviz Il, the Kisra of Persia, to the kings of Egypt and Abyssinia, the chiefs of Yemen and Syria. These letters have been preserved and reproduced by Arab chroniclers.

The letter to Heraclius, which was carried by Dahiyah al-Kalbi, read as follows:

In the name of God, the Beneficent, the Merciful. From Muhammad, the slave and Messenger of Allah, to Heraclius, the emperor of Rome. Peace be on him who follows the guidance. After this, I invite you to accept Islam. Accept Islam and you will prosper and Allah will give you double rewards. But if you refuse, the sin of your people also will fall on your shoulders. O People of the Book! Come to a word common between us and you: that we shall not worship anything save Allah, and that we shall not associate anything with Him, nor shall some of us take others for lords besides Allah. But if they turn back, then say: Bear witness that we are Muslims.

Herachus wanted to know more about this religion, so he summoned some Arab merchants who had come to Gaza with a caravan. Abu Sufyan, one of the bitterest enemies of the Prophet, happened to be in that group, so he became its spokesman. The conversation that took place between Heraclius and Abu Sufyan is preserved in the books of traditions:

Herachus: Is the family of the person claiming prophethood a noble one?

Abu Sufyan: It is a noble family.

Heraclius: Has anyone else in", this family claimed prophethood?

Abu Sufyan: No.

Heraclius: Has there been any king in this family?

Abu Sufyan: No.

Heraclius: Are the people who have accepted this religion weak or influential?

Abu Sufyan: They are weak people.

Heraclius: Are his followers increasing or decreasing?

Abu Sufyan: They are on the increase.

Heraclius: Have you ever known him to tell lies?

Abu Sufyan: No.

Heraclius: Does he ever commit a breach of any pact?

Abu Sufyan: He has not done it so far, but we would like to see if he keeps up a new peace treaty that we have recently negotiated with him.

Heraclius: Have you ever fought against him?

Abu Sufyan: Yes.

Heraclius: What was the result?

Abu Sufyan: Sometimes we won and sometimes he.

Heraclius: What does he teach?

Abu Sufyan: He bids people to worship one God and not to associate any partners with Him, to offer prayers, to be truthful and chaste, and to bestow alms.

Heraclius then summed up the conversation thus:

"You say that this man belongs to a noble family. Prophets always come from noble families. You say that no one else in the family ever before claimed prophethood. Had it been so, I would have thought that he was influenced by family traditions. You say that none of his predecessors was a king. Had it been so, I would have thought that he was aspiring to attain kingship. You admit that he never tells lies. A person who does not tell a lie to a man cannot tell a lie about God. You say that poor people are the adherents of his creed. The first followers of prophets always come from this class. You say that his religion is expanding. This is a characteristic of a true religion. You say that he does not deceive. Prophets do not deceive anyone. You say that he bids you to offer prayers and to observe purity and chastity. If all this is true, his realm will come right up to my domain. I had thought that a prophet might be coming, but I did not think that he would be born in Arabia. If I could go there, I would have paid homage to him."

Abu Sufyan used to say that he had to give true answers to the emperor, as he was afraid of being contradicted by one or more of his caravan companion if he gave any false reply.

The envoy sent to Khusro Parviz met a different reception. Khusro Parviz was enraged at the very idea of an ordinary person addressing him, the great Kisra that he was, on terms of equality, so he tore the letter to pieces. Kisra directed his governor of Yemen to arrest the person claiming to be a prophet and to send him to his court. When the governor's messengers arrived at Medina and asked the prophet to comply with Kisra's orders on pain of his country's destruction, the Prophet replied, "Go back and tell him that the Islamic empire will reach the throne of Kisra's kingdom." Not many years had passed when this prophecy came true.

The envoy sent to Harith, chief of the Ghassan tribe ruling Syria, was put to death. This eventually became the cause of a conflict with the Christians which resulted in the Battle of Mu'tah and the expedition of Tabuk.

The Prophet sent an epistle to al-Mundhir, the then Iranian Governor of Bahrain. It read as follows:

In the name of Allah, the Beneficent, the Merciful. From Muhammad the Messenger of Allah to al-Mundhir son of Sawa. Peace on him. Praise be to Allah besides Whom there is no other god. And I bear witness that there is no god except Allah and that Muhammad is His servant and messenger. And now I remind you of Allah, the Mighty and the Glorious. Whoever receives admonition receives it for his own good, and whoever obeys my envoys and follows their instructions obeys me. Whoever is sincere to them is sincere to me. My envoys have spoken well of you. I have accepted your intercession on behalf of the people of Bahrain. Leave to the Muslims all they owned before accepting Islam. While I hereby grant indemnity to the wrongdoers, you should also forgive them. You shall not be deposed so long as you conduct yourself well. And whosoever continues following his (religion of) Judaism shall be liable to pay the jizyah (defence tax).

The letter sent earlier to Negus, the king of Abyssinia, had read as follows:

In the name of Allah, the Beneficent, the Merciful. From Muhammad the Messenger of Allah to Negus, the king of Abyssinia. Peace be on him who follows the path of Guidance. Praise be to Allah besides Whom there is no other god, the Sovereign, the Holy One, the Preserver of Peace, the Keeper of the Faithful, the Guardian. I bear witness that Jesus son of Mary is indeed a spirit of God and His word, which He conveyed unto the chaste Virgin Mary. He created Jesus through His word just as he created Adam with His hands. And now I call you to Allah Who is One and has no partner, and to friendship in His obedience. Follow me and believe in what has been revealed to me, for I am the Messenger of Allah. I invite you and your people to Allah, the Mighty, the Glorious. I have conveyed the message, and it is up to you to accept it. Once again, peace on him who follows the path of guidance.

Another epistle sent to Muqauqis, the then Roman Viceroy over Egypt, was as follows:

In the name of Allah, the Beneficent, the Merciful. From Muhammad, the servant and Messenger of Allah to Muqauqis, Chief of the Copts. Peace be on him who follows the path of Guidance. I invite you to accept the message of Islam. Accept it and you shall prosper. But if you turn away, then upon you shall also fall the sin (of misleading by your example) the Copts. O people of the Book! Come to a word common between us and you: that we shall worship none but Allah and that we shall ascribe no partners unto Him and that none of us shall regard anyone as lord besides God. And if they turn away, then say: Bear witness that we are Muslims.