I was walking with the Messenger of Allah ﷺ when he came to a refuse heap belonging to some people and urinated while standing. I withdrew from him, but he called me over, and I stood near his heels until he finished. Then he performed ablution and wiped over his leather socks.
أخبرنا إسحق بن إبراهيم قال أنبأنا عيسى بن يونس قال أنبأنا الأعمش عن شقيق
كنت أمشي مع رسول الله ﷺ فانتهى إلى سباطة قوم فبال قائما فتنحيت عنه فدعاني وكنت عند عقبيه حتى فرغ ثم توضأ ومسح على خفيه
[Agreed upon. Bukhari narrated it, Book of Wudu, Chapter on Urinating Standing and Sitting, no. (224), and Muslim, Book of Purification, Chapter on Wiping over the Socks, no. (273), from the hadith of Amash through this same route. It is also in Al-Kubra, no. (18)].