Sunan Abi Dawud — The Rites of Hajj (Kitab Al-Manasik Wa'l-Hajj) — Hadith No: 1956
Translation
Narrated Rafi' ibn Amr al-Muzani: I saw the Messenger of Allah (ﷺ) addressing the people at Mina (on the day of sacrifice) when the sun rose high (i.e. in the forenoon) on a white mule, and Ali (Allah be pleased with him) was interpreting on his behalf; some people were standing and some sitting