سنن النسائي

It was narrated that Ash-Sha'bi said: "I heard Abu Juhaifah say: 'We asked 'Ali: "Do you have anything from the Messenger of Allah (ﷺ) apart from the Qur'an?" He said: "No, by the One who splits the seeds and creates the soul, unless Allah gives a slave understanding of His Book, or except this sheet." I said: "What is in the sheet?" He said: "In it are (the regulations concerning) blood money and the freeing of captives and (the rule) that no Muslim should be killed for killing a disbeliever."