Sahih Muslim 318
Sahih Muslim · Book 3: The Book of Menstruation · Description of ghusl in the case of janabah (sexual impurity)
'A'isha reported:
وَحَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى الْعَنَزِيُّ ، حَدَّثَنِي أَبُو عَاصِمٍ ، عَنْ حَنْظَلَةَ بْنِ أَبِي سُفْيَانَ ، عَنِ الْقَاسِمِ ، عَنْ عَائِشَةَ ، قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا اغْتَسَلَ مِنَ الْجَنَابَةِ دَعَا بِشَىْءٍ نَحْوَ الْحِلاَبِ فَأَخَذَ بِكَفِّهِ بَدَأَ بِشِقِّ رَأْسِهِ الأَيْمَنِ ثُمَّ الأَيْسَرِ ثُمَّ أَخَذَ بِكَفَّيْهِ فَقَالَ بِهِمَا عَلَى رَأْسِهِ .
When the Messenger of Allah (ﷺ) took a bath because of sexual intercourse, he called for a vessel and took a handful of water from it and first (washed) the right side of his head, then left, and then took a handful (of water) and poured it on his head.