Musnad Ahmad 626:17

'Affan narrated to us, Hammad ibn Salamah narrated to us, 'Asim ibn Bahdalah and Hammad informed us, from Abu Wa'il, from al-Mughirah ibn Shu'bah: "The Messenger of Allah (ﷺ) came to the trash heap of the sons of so-and-so, and he urinated while standing." Hammad ibn Abi Sulayman said: "And he spread his legs."