He replied:

Praise be to Allah, Lord of the worlds. He has not sinned by doing so; rather, he has done what he was commanded to do. If someone fears that using cold water will cause him a headache, a cold, or some other illness, and he cannot bathe in warm water, he should perform dry ablution—even if he is in a state of major ritual impurity—and pray. This is the view of the overwhelming majority of Muslim scholars, including Mālik, al-Shāfiʿī, Ahmad ibn Hanbal, and others.

Even if he regularly offers prayers at night and enters a state of major ritual impurity while the water is so cold that using it would harm him, he should perform dry ablution, offer his regular voluntary prayers, and recite the Quran both within and outside prayer. He should not miss his regular devotions because he is unable to bathe with water.

Must he repeat the obligatory prayer? There are two views:

The first is that he need not repeat it. This is the view of Mālik and one of the two positions reported from Ahmad.

The second is that he must repeat it. This is the view of al-Shāfiʿī and the other position reported from Ahmad. This applies when he is not travelling. As for a traveller, there is even stronger reason for him not to repeat it; this is one of al-Shāfiʿī’s two views.

Anyone permitted to pray after performing dry ablution is, with even greater reason, permitted to recite the Quran and remain in the mosque. The correct view is that he need not repeat the prayer, nor need anyone who has prayed according to