Sahih Muslim Book - 3, Hadith - 725

و حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى الْعَنَزِيُّ حَدَّثَنِي أَبُو عَاصِمٍ عَنْ حَنْظَلَةَ بْنِ أَبِي سُفْيَانَ عَنْ الْقَاسِمِ عَنْ عَائِشَةَ قَالَتْ كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ إِذَا اغْتَسَلَ مِنْ الْجَنَابَةِ دَعَا بِشَيْءٍ نَحْوَ الْحِلَابِ فَأَخَذَ بِكَفِّهِ بَدَأَ بِشِقِّ رَأْسِهِ الْأَيْمَنِ ثُمَّ الْأَيْسَرِ ثُمَّ أَخَذَ بِكَفَّيْهِ فَقَالَ بِهِمَا عَلَى رَأْسِهِ.

It was narrated that 'Aishah said: "When the Messenger of Allah (s.a.w) performed Ghusl from Janabah, he would call for something like a vessel used for milking, and take water in his palm. He started with the right side of his head, then the left. Then he took water in both palms and poured it all over his head."