Musannaf Ibn Abi Shayba 13:1109

Abu Bakr narrated to us, he said: Yahya ibn Yaman narrated to us, from Muhammad ibn Qays, from Bakkar al-Atari, that a man placed a restriction (hajr) upon a slave of his. The matter was raised to Ali, and he said, "Did you used to send him with a dirham to buy meat with it?" He said, "Yes." He said, "Then consider him authorized."