Yūsuf and others. Muhammad ibn al-Hasan, however, did not permit this, on the grounds that the state of someone who has performed dry ablution is deficient.

Furthermore, the beginning or end of the prayer time, without any new cause arising, has no effect in invalidating obligatory purification, since the state of the purified person is the same before and after the prayer time begins. The Lawgiver is wise: He establishes and sets aside rulings only for reasons appropriate to them. Just as He does not invalidate purification on account of place, He does not invalidate it on account of time or other circumstances that have no legal significance.

If it is said:

“This is contradicted by the purification of someone who wipes over his leather socks, that of a woman experiencing non-menstrual bleeding, and that of people with continuous causes of ritual impurity.”

The answer is:

Purification by wiping over leather socks is not obligatory. Rather, a person has the choice between wiping over them and removing them and washing his feet. This is why the Lawgiver imposed a time limit upon it. He did not tie that limit to the beginning or end of a prayer time; rather, because it is a concession, not a binding requirement, He prescribed a fixed duration for it: three days for a traveller, and one day and one night for a resident. This is also why wiping over leather socks is not permissible for major ritual purification.

By contrast, since purification by wiping over a splint is a binding requirement, no time limit was imposed upon it. A person may continue wiping over it until he removes it, and may do so for both minor and major ritual purification, just as dry ablution may be performed for both minor and major ritual impurity. It is therefore more appropriate to draw an analogy between dry ablution and wiping over a splint than between dry ablution and wiping over leather socks.