impure, or some of the flows are pure and some are impure, and there is no continuous two qullahs of pure water, then the evident (zahir) position of the school is that everything is impure, even if it is vast. It is also possible that it is pure, which is the position of al-Shafi'i; due to his saying (peace and blessings of Allah be upon him): "When water reaches two qullahs, it does not carry impurity." Also, because it is a large amount of water that has not been changed by impurity, it is therefore pure, just as if it had been changed and the change had ceased due to it remaining stationary.

Our position is that the impure has joined the impure, so the whole has become impure like things other than water. If some of the flows are pure but are small, it is of the type that does not repel impurity from itself, so it is even less likely to repel it from others.

If the water is vast and has been changed by impurity, but its change ceases by itself, the whole becomes pure. If it ceases due to a small amount of pure water less than two qullahs, or by the gathering of impure water into it, then the evident position of the school is that it is impure; because it does not repel impurity from itself, so it does not repel it from others. It is possible that it becomes pure; because it has removed the cause of impurity, thus the impurity is removed, just as if it had been removed by drawing out the water or by it remaining stationary.

Section: On purifying impure water, and it is of three categories:

One of them is that which is less than two qullahs; its purification is by adding an abundance of two pure qullahs, either by pouring them into it or by them spring-fed into it. Thereby, its change is removed if it were changed. If it were not changed, it becomes pure merely by the addition of the abundance; because two qullahs do not carry impurity, and they do not become impure except through being changed. For this reason, if impure water were to flow into them, it would not make them impure as long as they were not changed by it; likewise, if they are the ones flowing into it. It is a necessity of the ruling of their purity that that with which they are mixed becomes pure.

Second category: that which is exactly two qullahs. It is either not changed by impurity, in which case it becomes pure by the aforementioned addition of abundance and nothing else. The second is that it is changed, in which case it becomes pure by one of two things: by the aforementioned addition of abundance [if it removes the change], or by leaving it until its change ceases due to the length of time it remains stationary.