Musannaf Ibn Abi Shaybah

Hazrat Salim narrates from his father that the Holy Prophet (peace and blessings be upon him) wrote down the rulings of Zakat and placed them with his sword, or (the narrator is in doubt) with his will, and he did not send it out to the officials until the Prophet (peace and blessings be upon him) departed from this world. Then Hazrat Abu Bakr strictly followed it until his death, then Hazrat Umar also followed it. In it was written regarding the Zakat of goats that for three hundred goats, three goats are due as Zakat, and if the goats exceed this number, then for every hundred goats, one goat will be given. And if the goats exceed this number, then for every hundred goats, one goat will be given. Nothing is obligatory on less than one hundred.