كَانَ النَّبِيُّ صلى الله عليه وسلم إِذَا خَرَجَ لِحَاجَتِهِ أَجِيءُ أَنَا وَغُلاَمٌ مَعَنَا إِدَاوَةٌ مِنْ مَاءٍ. يَعْنِي يَسْتَنْجِي بِهِ.
Anas ibn Malik reported: When the Prophet ﷺ went out to relieve himself, I would come along with a boy, and we had a leather vessel of water with us. He means: he would clean himself with it.
also in Sahih al-Bukhari 151, Sahih al-Bukhari 152, Sahih al-Bukhari 217, Sahih al-Bukhari 500