As for people with continuous causes of ritual impurity, such as a woman experiencing non-menstrual bleeding, the cause that necessitates ritual impurity is present in their case: impure matter issuing from either the front or rear passage. Out of necessity, however, the Lawgiver has permitted them to pray despite this, so the concession may be time-limited. Thus, if a woman experiencing non-menstrual bleeding purifies herself and no discharge occurs, her purification is not invalidated when the prayer time ends. It is invalidated only if discharge has occurred during that time: she may pray with that purification until the prayer time ends, but thereafter she may no longer do so, because something that invalidates purification has occurred. This differs from someone who has performed dry ablution, since nothing has occurred after his dry ablution to invalidate his purification.

Dry ablution is like ablution with water: nothing invalidates it except what invalidates ablution with water, so long as the person remains unable to use water. This argument proceeds on the basis of our position, and that of those who agree with us, concerning the time limit for wiping over leather socks and the invalidation of ablution in the case of a woman experiencing non-menstrual bleeding. This is the position of the three imams: Abū Hanīfah, al-Shāfiʿī and Ahmad. As for someone who does not regard purification as invalidated by this, or does not impose this time limit, such as Mālik, a person holding that position cannot invoke either case as a counterargument. Neither is subject to a time limit in his view, so dry ablution has still stronger grounds for not being time-limited.

As for the assertion:

“A person who rises to pray is commanded to perform one of the two forms of purification.”

The reply is:

Yes, he is obliged to do so. But if he has purified himself beforehand, then he has already