It is narrated from Sayyiduna Abu Talhah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) sacrificed two piebald (black and white) rams. At the first he said: "On behalf of Muhammad and the family of Muhammad," and at the second he said: "On behalf of those of my Ummah who believed in me and affirmed me."
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 4719