From Sahih Muslim (Hadith 3100):
Usama b. Zaid (Allah be pleased with him) reported:Allah's Messenger (ﷺ) on his way back from 'Arafat got down in one of these creeks (to answer the call of nature), and after he had done that I poured water (over his hands) and said: Are you going to pray? Thereupon he said: The place of prayer is ahead of you
Reference: Muslim 3100