it remains purifying; but if a person deliberately puts them into it, it becomes pure but not purifying.

It is well known that when something’s ruling changes because it has changed, there is no distinction between something from which it is difficult to protect the water and something from which it is not difficult to protect it, nor between what was put into it deliberately and what was put into it unintentionally. This is just as we say when water is changed by an impurity: there is no distinction between an impurity from which it is difficult to protect the water and one from which it is not difficult to protect it, nor between what was put into it deliberately and what was not put into it deliberately, so long as the effective cause is the water’s having changed.

“Or if a state of ritual impurity is removed by a small amount of it, …”

His statement, “or if a state of ritual impurity is removed by a small amount of it,” means: if a state of ritual impurity is removed by a small quantity of water—namely, less than two qullahs—whether the ritual impurity affects all the limbs or only some of them. For example, a man has a vessel containing less than two qullahs of water and wishes to perform wudu. After scooping some out, he washes his hands; then he scoops out more and washes his face. Up to this point, the water has not become pure but not purifying. Then he immerses his forearm in it, intending by this immersion to remove the ritual impurity, and withdraws his hand. At that point, the ritual impurity has been removed from his hand, so it is true that a state of ritual impurity has been removed by a small quantity of it; consequently, it becomes pure but not purifying.

There is no evidence for this, only a line of reasoning: namely, that this water has been used for purification and therefore may not be used for purification a second time, just as a slave, once emancipated, cannot be emancipated a second time. This reasoning is unsound for two reasons:

First: there is a difference between the basis and the case being analogized to it. The basis upon which the analogy is made is the emancipated slave: once we have emancipated him, he no longer remains a slave. But when a state of ritual impurity has been removed by a small quantity of this water, it remains water; thus the analogy is invalid.

Second: a slave may return to slavery if he flees to