Chapter on the Virtue of Mosques and Prayer Within Them, and the Virtue of Congregational Prayer and Its Rulings

Al-Husayn ibn Sa’id from Muhammad ibn Mihran from Abdullah ibn Sinan from Abu Abdillah عليه السلام, peace be upon him, who said: I said to Imam al-Sadiq عليه السلام: “A man is in the mosque in prayer and wants to spit.” Imam عليه السلام said: “To his left. And if he is not in prayer, then he should not spit facing the Qiblah, but he may spit to his right or to his left.”