What should a Muslim do if he wakes up after a wet dream for Fajr prayer, and the water is very cold, such that performing ghusl with it would harm him, or if he cannot find water? Should he wait for the water to be heated, thereby missing the prayer time, or should he perform tayammum?

Scholars have differed regarding one who fears perishing or harm from using cold water. Malik held the view that one should prioritize tayammum (dry ablution) and prayer, citing the consensus of Muslims on the permissibility of tayammum for one who knows that water is unavailable until the time of the prayer expires. Whereas the majority held the view that purification should be prioritized, even if the time of the prayer expires, citing the generality of the verse: "And you find no water, then perform tayammum" (Quran 4:43), and the hadiths that prohibit tayammum when water is available and one is able to use it. This view is the most preponderant.

As for one who lacks water in urban areas, the most preponderant view is that he should perform tayammum and pray. This is the madhhab (school of thought) of Malik, Shafi'i, and Ahmad. If he prays with tayammum and then finds water, the most preponderant view is that he does not need to repeat the prayer.

As for the traveler who lacks water, he is permitted to perform tayammum. This is the madhhab of Malik, Shafi'i, and Ahmad, whether the journey is short or long. If the traveler prays with his tayammum and then finds water, he does not need to repeat the prayer, whether he finds it within the time of the prayer or outside it. This is the madhhab of the four Imams and the majority of the early and later scholars, and it is the most preponderant view.

Scholars have differed on the preference of performing tayammum early or delaying it: Ahmad held the view of delaying tayammum in all cases. Malik held the view that it is recommended if one expects to find water. Shafi'i held the view that praying with tayammum is better unless one is certain of finding water at the end of the prayer time.