I say: This is the stronger view, and Allah knows best. Running water is governed by the same ruling as still water, and in the Imām’s earlier opinion it is not rendered impure unless its properties change. The measure of two qullahs is, on the soundest position, approximately five hundred Baghdādī ratls. An effective alteration—whether produced by something pure or impure—concerns taste, color, or smell.

If pure water becomes mixed up with impure water so that the two cannot be distinguished, one exercises judgment (ijtihād) and purifies himself with the water he deems probably pure. A second view states that if water whose purity is certain is available, recourse to conjecture is impermissible. The blind person is treated like the sighted one on the stronger opinion.

When the uncertainty lies between water and urine, the correct view is that he does not attempt to choose; instead, the two are poured together and he performs tayammum (dry purification). If the uncertainty is between water and rosewater, he performs ablution with each vessel once. A different view allows him to exercise judgment.

After using the water he judged to be pure, he discards the other. If he keeps it and later changes his mind, he may not rely on that second assumption; rather, he performs tayammum, and—according to the soundest view—does not have to repeat his previous purification.

If someone whose report is accepted for transmission tells him the water has become impure and explains how, or if the informer is a qualified jurist of the same school, he may rely on that information.

The use of any clean vessel is permissible except those made of gold or silver, whose use is forbidden; according to the sounder view, even acquiring such vessels is likewise forbidden. Plated vessels are permissible on the soundest opinion, and precious materials such as ruby are permissible on the more apparent view.

As for an object banded with gold or silver: if the band is large and purely ornamental, it is unlawful; if it is small and only as much as need requires, it is not. Where the band is small but decorative, or large yet serves a genuine need, it is permissible on the soundest view. A band situated at the point of actual use is treated like any other band, according to the soundest opinion.

I say: the authoritative doctrine is that a gold band is forbidden in every case, and Allah knows best.