From Sahih Muslim (Hadith 1413):
Abu Umama b. Sahl reported:We offered the noon prayer with Umar b. 'Abd al-'Aziz. We then set out till we came to Anas b. Malik and found him busy in saying the afternoon prayer. I said to him: O uncle! which is this prayer that you are offering? He said: It is the afternoon prayer and this is the prayer of the Messenger of Allah (ﷺ) that we offered along with him
Reference: Muslim 1413