Bulugh al-Maram
Narrated Anas (rad): Whenever Allah’s Messenger (ﷺ) went to the privy, a servant and I used to carry a skin water container and a spear, and he would cleanse himself with the water. [Agreed upon].
وَعَنْهُ قَالَ: { كَانَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -يَدْخُلُ اَلْخَلَاءَ, فَأَحْمِلُ أَنَا وَغُلَامٌ نَحْوِي إِدَاوَةً مِنْ مَاءٍ وَعَنَزَةً, فَيَسْتَنْجِي بِالْمَاءِ } مُتَّفَقٌ عَلَيْه ِ 1 .
Reference