Bulugh al-Maram, Book 1, Hadith 95 (English)

Narrated Anas (rad): Whenever Allah’s Messenger 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 ِ (105)‏.‏ ‏4 ‏- صحيح.‏ رواه البخاري (150)‏، ومسلم (271)‏، (70)‏ واللفظ لمسلم.‏ والعنزة: رميح بين العصا والرمح، فيه زج.‏

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also referenced under: Book 1, Hadith 107 (In-Book)