Muhammad bin Ahmad bin Yahya from al-’Amraki from Ali bin Ja’far from his brother (Imam) Musa bin Ja’far عليه السلام, peace be upon them, who said: I asked Him عليه السلام about a man who remembered, while he was in his prayer, that he had not performed ‘istinjaʾ’ after relieving himself. Imam عليه السلام said: "He should leave, perform ‘istinja’ after relieving himself, and repeat the prayer."