Likewise, when an aquatic creature that has flowing blood—such as a fish or a frog—dies in the water, its death does not corrupt the water unless the odor changes. Should the smell change or the water become putrid, it is not permissible to use it for ritual bathing or for wuḍūʾ; yet, in Mālik’s view, the water is not intrinsically impure.
Used water remains pure so long as the limbs washed with it were themselves clean. Even so, Mālik and a group of eminent jurists regarded performing wuḍūʾ with such water as disliked. Mālik—may Allah have mercy on him—said, “There is no good in it, and I do not like anyone to perform wuḍūʾ with it; but if he does so and prays, I do not require him to repeat the prayer, though he should make a new wuḍūʾ for subsequent acts of worship.”
He likewise held that no one should perform wuḍūʾ with water from which a dog has lapped when other water is available. Although his statements on this point differ, the sound ruling in his school is as follows: he distinguishes, concerning the washing of a vessel a dog has licked, between dogs that may be kept and those that may not. In essence, he considers the dog itself pure and its lapping does not render impure whatever it licks—be it food or something else—yet he recommended discarding any water the dog has lapped because water is easily replaced. A desert dog and a town dog are the same in this regard, and the vessel must be washed seven times in every case, as an act of devotional obedience. This is the position that became authoritative among the scholars of his school who debated the matter.
Ibn Wahb relates in his recension of the Muwaṭṭaʾ that Mālik told him, “No one should perform wuḍūʾ with the remainder of a dog’s water, whether the dog is aggressive or not, unless the water is abundant, like the large cisterns.” If a person has two vessels, one of them impure though he does not know which, and he performs wuḍūʾ from one and prays, then washes his limbs with the second, performs wuḍūʾ with it, and prays, that is acceptable—although others have said he should simply pour the water away.