Bulugh al-Maram, Book 1, Hadith 96 (English)

Narrated Al-Mughira bin Shu’ba (rad): Allah’s Messenger told me, “Take the skin water”, he then went forward till he disappeared from me and relieved himself [Agreed upon]

وَعَنْ اَلْمُغِيرَةِ بْنِ شُعْبَةَ ‏- رضى الله عنه ‏- قَالَ: { قَالَ لِي اَلنَّبِيُّ ‏- صلى الله عليه وسلم ‏- "خُذِ اَلْإِدَاوَةَ" .‏ فَانْطَلَقَ حَتَّى تَوَارَى عَنِّي, فَقَضَى حَاجَتَهُ } مُتَّفَقٌ عَلَيْه ِ (106)‏.‏ ‏5 ‏- صحيح.‏ رواه البخاري (363)‏، ومسلم (274)‏ (77)‏.‏

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also referenced under: Book 1, Hadith 108 (In-Book)