Musannaf Ibn Abi Shayba 7:166

Ibn Fudayl narrated to us, from al-A’mash, from Muslim, from Masruq, who said: An udder was brought to ‘Abdullah while we were with him. A man from the people withdrew. ‘Abdullah said: "Draw near." The man said to him: "I have sworn that I will not eat the udder of a she-camel." He said: "Draw near and eat."