Thawr bin Qudamah (may Allah have mercy on him) said: A letter of Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) came to us, saying that we should eat only the cheese made by the People of the Book.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19691