Musannaf Ibn Abi Shayba 1:1137

Abu Mu'awiyah narrated to us, from al-A'mash, from Abu al-Duha, from Masruq, from al-Mughirah ibn Shu'bah, who said: I was with the Prophet, may Allah bless him and grant him peace, on a journey. He said: "O Mughirah, take the water container." He said: So I took it. Then I went out with him, and the Messenger of Allah, may Allah bless him and grant him peace, went on until he disappeared from my sight, and he relieved himself.