It is narrated from Sayyiduna Jubayr bin Mut'im (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "The whole of Mina is a place of sacrifice, and all the days of Tashriq (11th, 12th and 13th Dhul-Hijjah) are days of slaughter."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 10226