Sunan Ibn Majah, Chapter: The Chapters of Purification and its Sunnah

that his father said: "I was with the Prophet (saw) on a journey, and he wanted to relieve himself. He said to me: 'Go to those two small date-palm trees and tell them: "The Messenger of Allah (saw) orders you to come together:'" So they came together and he concealed himself behind them, and he relieved himself. Then he said to me: 'Go to them and tell them: "Go back, each one of you, to your places.'" So I said that to them and they went back." (Hasan)