Musannaf Ibn Abi Shayba 16:192

Abu Bakr narrated to us, he said: Abu Mu'awiyah narrated to us, from al-A'mash, from Shaqiq, from 'Amr ibn Shurahbil, who said: We mentioned cheese in the presence of 'Umar, and we said to him: "Indeed, the rennet of a dead animal is used in it." He said: "Mention the name of Allah over it and eat it."