the limbs have dried. This is based on the view that continuity in ablution is not a condition.

The fourth view—favored by Shaykh al-Islam (1)—is that purification is not invalidated, whether continuity has been interrupted or not, unless one of the known nullifiers of ablution occurs. However, in this case he may not put them on again in order to begin wiping over them anew. For if that were allowed, specifying a time limit for wiping would serve no purpose: anyone wishing to continue wiping could simply remove his leather socks, put them back on, and then begin a new period. . . .

Its proof is that this state of purification was established by legal evidence, and whatever is established by legal evidence is not invalidated except by legal evidence. Otherwise, the basic presumption is that purification remains valid. This view is correct. It is further supported by analogy: if a man has abundant hair and wipes over his hair in such a way that no moisture reaches the inner part of his head, then shaves his hair after ablution, his purification is not invalidated.

If it is said: Wiping over the head is the original ruling, whereas wiping over leather socks is a concession derived from it; how, then, can the original and the derivative be treated alike?

The answer is that, once wiping has been connected to something that has subsequently been removed—and we agree on this point—whether it is an original ruling or a derivative one has no effect on the ruling.

Or if its period expires, he must renew his purification.

His statement, “or if its period expires, he must renew his purification,” means that when the period expires, even if he is in a state of purity, he must renew his purification if he wishes, for example, to pray.