Musannaf Ibn Abi Shayba 16:200

Abu Bakr narrated to us, he said: Ubaydah ibn Humayd narrated to us, from Ata’ ibn al-Sa’ib, from Sa’id ibn Ubaydah, who said: A man asked Ibn Umar about cheese. Ibn Umar said to him: "Eat the cheese and drink it." He said: "Indeed, there is carrion in it." Ibn Umar said to him: "Then do not eat the carrion."