Nafi' bin Jubayr bin Mut'im narrates from one of the Companions (may Allah be pleased with him), whom Nafi' named but I forgot, that the Prophet (peace and blessings be upon him) said to a man from (the tribe of) Ghifar: "Stand and announce that none will enter Paradise except a believer, and that these days of Mina are days of eating and drinking." Sulayman bin Musa added: "and slaughter," meaning: they are days of slaughter.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19244