Musannaf Ibn Abi Shayba 13:3293

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Zam’ah narrated to us, from al-Zuhri, from Ibn Ka’b ibn Malik, from his father, that the Prophet, peace and blessings of Allah be upon him, passed by him while he was demanding a man for two uqiyas. The Messenger of Allah, peace and blessings of Allah be upon him, said to the man with his hand like this—meaning: "Relieve him of half of it." The man said: "Yes, O Messenger of Allah." He then said: "Pay him the remainder of his right."