From Sahih Muslim (Hadith 3103):
Usama b. Zaid (Allah be pleased with him) reported that when Allah's Messenger (may peace jbe upod him) came to the valley where the rich (people of Mecca) used to get down. he got down. and urinated (and he did not mention about pouring water) ; he then called for water and performed a light ablution. I said:Messenger of Allah, the prayer I Thereupon he said: Prayer awaits you ahead
Reference: Muslim 3103