Musannaf Ibn Abi Shayba 9:341

Abu Bakr narrated to us, he said: Sufyan ibn 'Uyaynah narrated to us, from al-Zuhri, from 'Ubayd Allah, from his father, who said: 'Umar was asked about combining a mother and her daughter from what the right hand possesses. He said: "I do not like to permit both of them together."