Musnad Ahmad 5:220

Hashim ibn al-Qasim narrated to us, Sharik narrated to us, from Mukhariq, from Tariq ibn Shihab, who said: I witnessed Ali, and he was saying upon the pulpit: "By Allah, we have no book that we read to you except the Book of Allah the Exalted, and this scroll"—which was hanging from his sword—"I took it from the Messenger of Allah, may Allah bless him and grant him peace; in it are the obligatory duties of charity." It was hanging from a sword of his that had iron ornamentation, or he said: its rings were of iron.