And this, I believe, is one of the two views held by the scholars of our school: if removing a leather sock would cause harm, it is treated like a splint. According to the other view, if he fears harm from removing it, he performs dry ablution (tayammum) rather than wiping over it.

This parallels the two positions transmitted within our school concerning someone with an exposed wound that he can wipe with water but cannot wash: should he wipe it or perform tayammum for it? There are two transmitted positions. The correct view is that he should wipe it, because purification by wiping with water takes precedence over purification by wiping with earth. Moreover, if wiping over a covering on a limb is permissible, wiping the limb itself is all the more appropriate.

The distinction is that purification by wiping over leather socks is available by choice, whereas purification by wiping over a splint is necessitated by circumstances. Since someone wiping over leather socks can either wash his feet or wipe over the socks, a time limit is set for his wiping. But since someone wiping over a splint has no alternative, no time limit is set, and wiping is also permissible when purifying himself from major ritual impurity. Thus, a leather sock whose removal would cause harm is treated as a splint.

Such harm may arise in several ways. A person may be amid snow and severe cold, such that removing his leather socks would expose his feet to harm. Or the water may be too cold for him to wash his feet, so that if he removed his socks, he would have to perform tayammum. Wiping over them is therefore better than tayammum.

Alternatively, he may fear that removing them and performing ablution would expose him to an enemy or a predatory beast, or leave him separated from his companions in a place where he cannot travel alone. In such circumstances, he may forgo purification with water and perform tayammum instead. It is therefore all the more permissible for him to forgo purification by washing in favour of wiping.

The same applies when he has no water apart from a small quantity sufficient for purification involving wiping, but not washing. If he removed his leather socks, he would have to perform tayammum; wiping over them is therefore better than tayammum.