What is the requirement regarding the number of stones used for Istijmar (cleansing with stones)?
Chapter on Cleaning oneself (Istitabah) and Impurity (Hadath)
Al-Mughni
Book of Purification
Primary text
It is obligatory to ensure purification (Inqa') is achieved, and that three stones are used. If purification is not achieved with three stones, one must increase the number until purification is complete. This is the established view of Al-Shafi'i and a group of scholars, based on the narration from Salman that the Prophet (PBUH) forbade using fewer than three stones for Istinja. If purification is achieved before three, it is insufficient, as both conditions—purification and the count of three—must be met.
Supporting text
Malik and Dawud held that purification alone is obligatory without adherence to a specific number, citing the Prophet's saying: "Whoever performs Istijmar, let him use an odd number. Whoever does so has done well, and whoever does not, there is no blame upon him." However, the primary evidence for requiring three stones overrides this.