The Messenger of Allah ﷺ addressed us on the Day of Sacrifice while mounted on a red she-camel with a clipped ear, and he said, "This is the Day of Sacrifice, and this is the day of the greatest Hajj."
خطبنا رسول الله ﷺ يوم النحر على ناقة له حمراء مخضرمة، فقال: هذا يوم النحر، وهذا يوم الحج الأكبر.
Ahmad (1588) narrated it from Waki, who said, Shuba narrated to us, from Amr bin Mura, from Mura Tayyib, who said, A man among the companions of the Prophet ﷺ narrated to me in this room of mine, I think he said (then he mentioned it). Its chain of transmission is sahih. Amr bin Mura is Amr bin Abdullah bin Tariq Jamali Muradi, one of the men relied upon by all the compilers.