1. An impurity is an intrinsically foul substance; once it is removed, the object returns to its state of purity.

2. Removing impurity is not a matter of carrying out a command; rather, it is a matter of avoiding what is prohibited. Thus, whenever it is achieved by any means whatsoever, the ruling is established. This is why intention is not stipulated for the removal of impurity. If rain falls upon impure ground and removes the impurity, it becomes pure. Likewise, if a person performs ablution while his forearm has been affected by impurity, then, after completing his ablution, remembers it and finds that it has been removed by the water of ablution, his arm is purified—except according to the madhhab, because they stipulate seven washings, whereas ablution is not performed with seven washings.

The response to the evidence cited by the Hanbalis is that no one denies that water is purifying, or that it is the easiest means by which things are purified. However, establishing that it is purifying does not preclude something else from also being purifying. We have a principle: the absence of a particular cause does not entail the nonexistence of a particular effect, for the effective cause may be something else. This is the case with impurity. Some have expressed the substance of this principle by saying: “The absence of a particular proof does not entail the absence of what it proves, for it may be established by another proof.”

As for the hadith of Anas and the Prophet’s ﷺ command that water be poured over it (1), that was in order to purify it promptly. The sun does not reach it immediately so as to purify it; rather, that requires days, whereas water purifies it at once. The mosque needs to be purified promptly, because it is the people’s place of prayer.