Muslims are taught to understand that human beings are fragile, weak, and prone to illness. We all get sick at one time or another, some more seriously than others. Although modern medicine has come a long way in preventing and curing illness, many people find comfort in prayer, as well.
Muslims see illness not as a punishment from Allah, but rather as a test and a purification of sins. Will you keep your faith strong despite your poor health?
Will you see your illness as a cause of despair, or as an opportunity to turn to Allah for mercy and healing?
Muslims may recite personal prayers (du'a) in any language, but these from Islamic tradition are most common.
Du'a From the Quran, prayer of Prophet Ayyub (Job)—Quran 21:83-84
‘an-nee mas-sa-ni-yaD-Dur-ru wa ‘AN-ta ‘Ar-Ha-mur-raa-Hi-meen.

Truly distress has seized me, but You are Most Merciful of those that are merciful.
Du'a From the Sunnah
Whenever the early Muslims became sick, they sought the advice of the Prophet Muhammad himself. It is related that when someone fell ill, the Prophet would recite one of these du'as for them.
#1: It is recommended to touch the area of pain with the right hand by reciting this supplication:
Allahuma rabbi-nas adhhabal ba'sa, ashfi wa entashafi, la shifa' illa shifa'uka shifa' la yughadiru saqama.

Oh Allah! The Sustainer of Mankind! Remove the illness, cure the disease. You are the One Who cures. There is no cure except Your cure. Grand us a cure that leaves no illness.
#2 Repeat the following du'a seven times:
'As'alu Allah al 'azim rabbil 'arshil azim an yashifika.

I ask Allah, the Mighty, the Lord of the Mighty Throne, to cure you.
#3: Another du'a from the Sunnah:
Rabbana 'atinaa fid dunyaa hasanat wafil aakhirati hasana taw wa qinaa azaaban naar.

Oh Allah! Our Lord and Sustainer! Grant us good in this world and good in the Hereafter, and save us from the Fire of Jahannam (Hell).
#4: This du'a should be recited while the sick person places his or her right hand on the area of pain. The word "bismillah" should be repeated three times, and the entire supplication should be recited seven times:
A'oozu bi'izzatillaahi wa qudratihi min sharri maa ajidu wa uhaaziru.
I seek protection in the might of Allah and His power from the evil of what I am experiencing and of what I fear.
Finally, no matter how great the pain, a Muslim should never wish for death or commit suicide. Rather, the Prophet Muhammad advised the Muslims as follows:
None of you should wish for death because of a calamity befalling him; but if he has to wish for death, he should say: "O Allah! Keep me alive as long as life is better for me, and let me die if death is better for me. "