Whenever the Prophet ﷺ went out to relieve himself, I and another boy would come along carrying a small water vessel, meaning he would use it to cleanse himself.
كان النبي ﷺ إذا خرج لحاجته أجيء أنا وغلام معنا إداوة من ماء. يعني يستنجي به.
Bukhari narrated it in the chapter on wudu (150), and this is his wording, and Muslim narrated it in the chapter on purification (271). Both narrated it through the route of Shubah, from Abu Muaz, who is Ata bin Abu Maymuna, that he heard Anas bin Malik say, and then he mentioned the hadith.Muslim's wording is, "The Messenger of Allah ﷺ used to go into the lavatory, and I, along with a boy about my age, would carry a small vessel of water and a staff, and he would cleanse himself with the water."In a hadith from someone other than Shubah, found in Muslim, "The Messenger of Allah ﷺ entered a walled garden, and a boy carrying a water vessel followed him, he being the youngest of us, and he placed it by a jujube tree. The Messenger of Allah ﷺ then relieved himself, and came out to us having cleansed himself with water."In another version found in Muslim, "The Messenger of Allah ﷺ used to go out to relieve himself, and I would bring him water, and he would wash himself with it."Explanation of terms, "anaza" refers to a long staff with an iron point at its lower end, also said to be a small spear. "Mida'ah" is the vessel used for performing wudu, similar to a small water jar or a pitcher and the like. "Sidra" is a jujube tree. "Yatabarraz" means he goes out to an open space, meaning a wide and clean stretch of ground, so that he may be private for his need and far from the eyes of onlookers. "Fa yataghassalu bihi" means he cleanses himself with it, washing the place used for cleansing.