Let him, and pour a bucket or pail of water onto his urine. You were sent to make things easy and not to make them difficult
Authentic hadithعن أبي هريرة رضي الله عنه قال: بال أعرابي في المسجد، فقام الناس إليه لِيَقَعُوا فيه، فقال النبي صلى الله عليه وسلم : «دعوه وأريقوا على بوله سَجْلاً من ماء، أو ذَنُوبًا من ماء، فإنما بُعِثْتُمْ مُيَسِّرِينَ، ولم تُبْعَثُوا مُعَسِّرِينَ».
Abu Hurayrah (may Allah be pleased with him) reported: A Bedouin man urinated in the mosque, so the people got up and moved towards him to scorn him. So the Prophet (may Allah's peace and blessings be upon him) said: "Let him and pour a bucket or pail of water onto his urine. You were sent to make things easy and not to make them difficult."
Explanation
A Bedouin man got up and started to urinate inside the Prophet’s Mosque. So, the people attacked him with their tongues, not with their hands; i.e. they shouted at him in scorn. So, the Prophet (may Allah's peace and blessings be upon him) asked them to leave him alone, and when the man finished urinating, the Prophet ordered them to pour a bucket of water over the place where he urinated, and explained to them that they were callers to facilitating matters, not to making matters difficult and thus causing people to turn away from guidance.
Source · Al-Bukhari and Muslim. This is the wording of Al-Bukhari
From the Hadith Encyclopedia (hadeethenc.com).