It is not haraam for a man to urinate standing up, but it is Sunnah for him to urinate sitting down, because -
‘Aa’ishah (may Allaah be pleased with her) said: “Whoever tells you that the Prophet (peace and blessings of Allaah be upon him) used to urinate standing up, do not believe him. He only ever used to urinate sitting down.”
(Narrated by al-Tirmidhi, al-Tahaarah, 12;
It was also classed as saheeh by al-Albaani in Saheeh Sunan al-Tirmidhi, no. 11). And because this is more concealing, and it reduces the risk of any drops of urine splashing up onto him. Muhammad did not mind semen splashing onto his clothes but objected to urine.
It was narrated from ‘Umar, Ibn ‘Umar and Zayd ibn Thaabit (may Allaah be pleased with them) that it is allowed to urinate standing up on the condition that there is no risk of drops of urine splashing onto one’s body or clothes, and that one does not expose one's ‘awrah, because al-Bukhaari and Muslim narrated from Hudhayfah (may Allaah be pleased with him) that the Prophet (peace and blessings of Allaah be upon him) came to a garden belonging to some people, and urinated standing up.Is it now Sunnah to pee while standing up in someone`s garden you happen to come across?When you go to the restroom, take three stones with you to clean yourself. That will suffice.”
(Abu Dawud)I presume that this refers to bowel movements but does it apply today? What happens to the stones when you have cleaned yourself?“The Prophet [while traveling] approached a garbage dump and stood while urinating. Then, he called me to bring some water for him, so I did, and he performed wuḍu’