Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates: Once the Prophet Muhammad (peace and blessings be upon him) went to relieve himself, and he instructed Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him): "Bring me three stones." Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) brought two stones and a piece of dung. The Prophet Muhammad (peace and blessings be upon him) threw away the dung and said: "This is filth, bring stones." The same narration is also transmitted with another chain, according to which Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates: Once I was walking with the Prophet Muhammad (peace and blessings be upon him). The narrator states: The Prophet Muhammad (peace and blessings be upon him) instructed me: "Bring me three stones." The narrator states: I brought two stones and a piece of dung to him, so the Prophet Muhammad (peace and blessings be upon him) put the dung aside and said: "This is filth, instead of this bring me something else (a stone)." In this narration, there is a disagreement regarding the narrator named Abu Ishaq. (Imam Daraqutni says:) I have clarified this disagreement elsewhere.