A person happened to pass by the Messenger of Allah (ﷺ) when he was making water and saluted him, but he did not respond to his salutation.
Sahih Muslim Book 3, Hadith 144
← Previous Hadith I and 'Abd al-Rahmin b. Yasir, the freed slave of Maimuna, the wife of the Apostle (way peace be upon him). came to the house of Abu'l-Jahm b. al-Harith al-Simma Ansari and he said: The Messenger of Allah (ﷺ) came from the direction of Bi'r Jamal and a man met him; he saluted him but the Messenger of Allah (ﷺ) made no response, till he (the Holy Prophet) came to the wall, wiped his face and hands and then returned his salutations.

Sahih Muslim Book 3, Hadith 143 Next Hadith → 0 Abu Huraira, where were you? He said: Messenger of Allah, you met when I was (sexually) defiled and I did not like to sit in your company before taking a bath. Upon this the Messenger of Allah (ﷺ) said: Hallowed be Allah, verily a believer is never defiled.

Sahih Muslim Book 3, Hadith 145