Hadith 61
It is narrated from Sayyiduna Hudhayfah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) came to a garbage dump (a heap of refuse), and he stood and urinated. Then the Prophet (peace and blessings be upon him) performed ablution and wiped over his leather socks.
Hadith 62
Abu Hazim narrates that I saw Sayyiduna Sahl bin Sa’d (may Allah be pleased with him) urinating while standing. After finishing, he explained the reason for his action by saying that he had seen someone better than himself do this (i.e., the Messenger of Allah, peace and blessings be upon him).