How is the condition for using stones (istijmar) to be an odd number (three or more than three) when there is a narration in Sahih al-Bukhari that the Prophet used two stones for istijmar?

Scholars have differed regarding the condition of a specific number for istijmar (cleansing with stones). The Shafi'is and Hanbalis hold that inqa' (thorough cleansing) and completing three stones are required. They cite as evidence traditions, among them: "Our Prophet, peace be upon him, forbade us from cleansing with less than three stones."

Conversely, the Hanafis and Malikis are of the view that only inqa' is obligatory, and using three stones is merely recommended. They base their argument on the hadith narrated by Bukhari concerning the story of Ibn Mas'ud and the Prophet's request for a third stone after two.

However, their argument has been rebutted by explaining that the Prophet, peace be upon him, ordered a third stone in place of the dung, and this is what many scholars have favored.

In conclusion, the preponderant opinion is that inqa' and completing three stones are required, and that a large stone with three facets can substitute for them, due to the strength of the evidence supporting this view.