Musannaf Ibn Abi Shayba 16:189

Abu Bakr narrated to us, he said: Jarir narrated to us, from Mughira, from Abu Wa'il and Ibrahim, they both said: When the Muslims arrived, they obtained some of the food of the Magians, from their cheese and their bread, so they ate and did not ask about that. The cheese was described to Umar, and he said: "Mention the name of Allah over it and eat it."