I was with the Prophet (may Allah's peace and blessings be upon him) when he arrived at the dump of some people and passed urine while standing

Hudhayfah ibn al-Yamān (may Allah be pleased with him and his father) reports that he was with the Prophet (may Allah's peace and blessings be upon him) who wanted to urinate and, thus, entered the dump of some people, i.e., a place where the garbage and the dust swept off homes are thrown. He passed urine while standing, although he would usually urinate while sitting.

Hudhayfah moved away, but he (may Allah's peace and blessings be upon him) said to him: Come close, and Hudhayfah moved close until he was standing behind his heels to act as a barrier for him and let no one see him in such a state. Then the Prophet (may Allah's peace and blessings be upon him) made ablution, and on reaching the point of washing the feet, he only wiped over both of his Khuffs - footwear made of soft leather and the like covering the heels—without taking them off.