Sufyan bin Hussain bin al-Hasan سفيان بن حسين السلمي · The Book on Zakat

"The Messenger of Allah had a letter written about charity, but he had not dispatched it to his governors until he died; he kept it with him along with his sword. When he died, Abu Bakr implemented it until he died, as did Umar until he died. In it was: 'A sheep (is due) on five camels, two sheeps on ten, three sheeps on fifteen, four sheeps for twenty, a Bint Makhad on twenty-five to thirty-five. When it is more…