Shu'bah narrates from a man of Banu Uqayl, who narrates from his paternal uncle, that a letter of Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) was read out to us, in which it was written: Eat the cheese made by the People of the Book.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19690