Harb bin Ubaydullah narrates from his father, and he from Abu Hamidah (may Allah be pleased with him), that the Messenger of Allah (peace and blessings be upon him) said: "The tithe, that is, the tenth, is not upon the Muslims; rather it is upon the Jews and the Christians."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجزية / 18773