the 'flow'; for it is in the position of impure water poured onto [an amount] less than two qullahs. Thus, when the stationary water becomes impure, that which passes over it becomes impure. It is also possible that a ruling of purity is applied to the 'flow' at the moment of its meeting the stationary water, and the stationary water does not become impure by it, because it is a large amount of water that has not changed, so it does not become impure; due to the saying of the Prophet (peace and blessings of Allah be upon him): "When water reaches two qullahs, nothing makes it impure." This is the position of al-Shafi'i.

This all applies as long as it has not changed. If it has changed, it is impure, and its ruling is the ruling of the substances of impurity itself. Therefore, if the stationary water is changed on its own, then the 'flow' that passes by it, if it is two qullahs, is pure; if it is less than two qullahs, it is impure. If the 'flow' is changed and the stationary water is two qullahs, it is pure, otherwise it is impure. If some of the stationary water is changed and some is not, and the unchanged part along with the 'flow' coming into contact with it is two qullahs, it does not become impure; because it is water exceeding two qullahs that has not changed, so it is pure, as if the 'flow' were two qullahs. If the changed part of the stationary water is adjacent to the two 'flows' and the unchanged part is not adjacent to it, nor connected to it from the top of the water, nor from its bottom, nor from any of its sides, and each of the two is less than two qullahs, then the whole should be impure; because everything that comes into contact with the impure water does not reach two qullahs. If it is connected to it from one side, then everything that has not changed is pure if it reaches two qullahs; because it is like two ponds between which there is a water channel. If one is in doubt about that, then the water is pure; because the foundational principle is purity, and it does not vanish due to doubt. And Allah knows best.

Section: If the 'flows' meet in one place, if it is changed by the impurity, it is impure, even if it is vast. If there is in some of the 'flows' pure water that is continuous and reaches two qullahs, whether it precedes [the impurity] or follows it, then the whole is pure, as long as it has not changed; because two qullahs repel impurity from themselves and from what they have gathered with. If that which is gathered is less than two qullahs, and in some of the 'flows' there is something impure, then the whole is impure according to the evident (zahir) position of the school.