The evidence for this is the hadith of Salman al-Farisi, may Allah be pleased with him, recorded in Sahih Muslim: “The Messenger of Allah, peace and blessings be upon him, forbade us to cleanse ourselves with fewer than three stones.” (1)

The reason he, peace and blessings be upon him, instructed the use of three stones is so that a person does not repeat the wiping with the same side, for if he does so, he gains no benefit; rather, he may become even more soiled.

Cleansing, or more, even with a stone having several sides ………

His statement, “cleansing,” refers to the sixth condition: cleansing is when the stone comes away dry and not moistened, or when only a trace remains that can be removed only by water.

His statement, “or more,” means that one wipes three times; if the three wipes do not cleanse, he adds more.

Some scholars said that if cleansing is achieved with fewer than three wipes, that suffices. (2) Their reasoning is that the ruling revolves around its effective cause. This view is rebutted by the fact that he, peace and blessings be upon him, forbade cleansing oneself with fewer than three stones; and if he forbade that, then one must not do what he forbade. Furthermore, it is generally the case that cleansing is not achieved with fewer than three stones, and because three is a fixed number to which the Lawgiver has attached many rulings.

His statement, “even with a stone having several sides”: the word “even” indicates a point of disagreement, because some scholars held that three separate stones are indispensable, (3) limiting themselves to the apparent wording of the hadith. There is no doubt that this is more complete in purification, since a multi-sided stone may have, on one of its sides, some residue from the wiping.