Designed to a In one word: Prevention.

One of the major goals of public health is to prevent the development of disease or the occurrence of injury in an effort to promote health. Thus, for example, most lung cancer is preventable. Public health efforts to help people stop smoking potentially could eliminate about 70% to 80% of lung cancer. The use of seatbelts, airbags, breakaway poles on highways, and other such modifications to motor vehicles and the environment have drastically reduced motor vehicles injuries, even though far more people drive. Simple things like installing lights in parking lots and requiring exact change on buses have reduced violence-related injuries. It is well known in public health that preventing adverse health consequences is far easier and more effective for health than treating someone who is ill or injured.

Similarly, one of the main goals of Shari’ah or Islamic law is to prevent corruption and evil in an effort to promote beneficence with the ultimate goal of the Hereafter. The Arabic term Shari’ah literally means "the broad path leading to water." In an Islamic sense, Shari’ah has been described as “the road to right activity that all Muslims have to follow. The water here is the heavenly water that purifies and saves…” (The Vision of Islam)

The principle sources of Shari’ah is foremost the Qur’an and then the Sunnah—i.e., the established practice or course of conduct of the Prophet Muhammad, may God bless him and grant him peace. When those sources do not directly address an issue or can be interpreted differently, Islamic scholars have relied on other principles such as consensus of opinion, analogy, consideration of public interest, custom, personal reasoning and more. Scholars differ over which of these methods is appropriate to use after the Qur’an and Sunnah and if used, how properly applied.

Another principle of Islamic jurisprudence known as sadd al-dhara’i provides a good example of the importance of prevention in Islam.

Sadd is an Arabic word which translates as “blocking”. Dhari’ah refers to the means to obtaining a certain end. Thus, sadd al-dhara’i "implies blocking the means to an expected end that is likely to materialise if the means towards it is not obstructed.” As a doctrine of Islamic jurisprudence, it refers to blocking the means to evil.

The whole concept of sadd al-dhara’i is founded in the idea of preventing an evil before it actually materialises. It is therefore not always necessary that the result should actually take place. It is rather the objective expectation that a means is likely to lead to an evil result that renders the means in question unlawful even without the realisation of the expected result. (Principles of Islamic Jurisprudence)

For example, trade and commercial transactions during the time of Jumu’ah (Friday congressional prayer) is prohibited as it might obstruct someone from attending the prayer, even if it does not actually occur. Similarly, illicit privacy among men and women is prohibited because it could lead to adultery or sexual intimacy outside of the marriage context, even if it does not lead to it.

Authority for the principle of sadd al-dhara’i is found in both the Qur’an and Sunnah. For example, in Surat al-Baqara (2:104) Muslims were told not address the Prophet Muhammad (saas) by the word ra’ina because it had two meanings, one of which was respectful and the other which non-Muslims used to insult the Prophet (saas). Thus, despite the good intention of the Muslims by using the word, its use was prohibited because of the evil result. Similarly, the Prophet Muhammad (saas) prohibited enforcing the punishment for theft during battles to avoid defection to enemy forces. In both cases, the means were lawful but they were prohibited to avoid potential harm.

The doctrine of sadd al-dhara’i is far more complicated than the brief explanation here. For example, the application of sadd al-dhara’i has also been used where the haram (forbidden) may be turned into the halal (permissible) if it is likely a greater evil will be prevented. Thus, a lesser evil is tolerated to prevent a greater one. For example, giving money to an enemy is not allowed as it can strengthen the enemy, but is permitted for the release of Muslim prisoners.

Moreover, sadd al-dhara’i is not the only place where prevention is evident in Islam. For example, the Qur’an specifies how war booty should be distributed among kindred of deceased, orphans, the needy, and wayfarer, “[i]n order that it may not (merely) make a circuit between the wealthy among you.” (Al-Qur’an, 59:7) This verse seeks to prevent the accumulation of wealth in a few hands.

Another example concerns what Muslim women wear. Most scholars agree that the Qur’an requires women to dress modestly, including covering their hair. Among other things, wearing a headscarf prevents exposure to harm. For example, at least in the United States, men tend not to curse, tell dirty jokes, or flirt with women who cover. The headscarf sends the message that such things would not be appreciated.

The point here is that although the commands and injunctions in Islam may not always be obvious, they often are instituted to prevent against those things that will ultimately lead to a bad result, both in this world and the Hereafter.