Musannaf Ibn Abi Shayba 9:1456

Abu Bakr narrated to us, he said: Ibn Idris narrated to us, from Muhammad ibn ‘Amr, from Abu ‘Ubaydah ibn ‘Abd Allah ibn Zam‘ah, from his mother, Zaynab bint Abi Salamah, who said: Asma’ had breastfed me. Ibn al-Zubayr used to enter upon me while I was combing my hair, and he would take a lock of my hair and say: "Turn to Muhammad with my hadith, for you think he is my father, but he is only the brother of my siblings." When the Day of al-Harrah occurred, ‘Abd Allah ibn al-Zubayr sent to propose to my daughter for Hamzah and al-Zubayr, and Hamzah and Mus‘ab for the Kalbiyyah. I sent to him: "Is she suitable for him?" He sent to me: "You only want to prevent me from your daughter, and I am your brother. Whatever Asma’ gave birth to, they are your siblings, and whatever al-Zubayr gave birth to from other than Asma’, they are not your siblings. So send and ask." I sent and asked, while the Companions of the Prophet (peace and blessings of Allah be upon him) were numerous, as well as the Mothers of the Believers. They said: "Indeed, breastfeeding from the side of the men does not make anything prohibited."