Bulugh al-Maram
Narrated Abu Sa’id Al-Khudri (rad): Allah’s Mesenger (ﷺ) said: “The water (of the ghusl) is due to the water (of sexual emission)”. [Reported by Muslim]
عَنْ أَبِي سَعِيدٍ اَلْخُدْرِيِّ - رضى الله عنه - قَالَ: قَالَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -{ اَلْمَاءُ مِنْ اَلْمَاءِ } رَوَاهُ مُسْلِم ٌ 1 .
Reference