Ghudayf bin al-Harith (may Allah have mercy on him) said that a governor wrote to Sayyiduna Umar bin al-Khattab (may Allah be pleased with him): "There are some people in our region who are called the Samaritans. They observe their religious rites on Saturday and recite the Torah, but they do not believe in the Day of Resurrection. O Commander of the Faithful, what is the ruling on their slaughtered animals?" So Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) wrote: "They are People of the Book; the ruling on their slaughtered animals is the same as that on the slaughtered animals of the People of the Book."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13989