Aisha reported: When the Prophet, peace and blessings be upon him, took a ritual bath for major impurity, he began by washing his hands, then he would perform an ablution as if for prayer. Then, he would put his fingers in the water and wash the roots of his hair with them, then he would pour three handfuls of water over his head and pour water all over his body.
Source: Ṣaḥīḥ al-Bukhārī 248
Grade: Sahih (authentic) according to Al-Bukhari
عَنْ عَائِشَةَ أَنَّ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ كَانَ إِذَا اغْتَسَلَ مِنْ الْجَنَابَةِ بَدَأَ فَغَسَلَ يَدَيْهِ ثُمَّ يَتَوَضَّأُ كَمَا يَتَوَضَّأُ لِلصَّلَاةِ ثُمَّ يُدْخِلُ أَصَابِعَهُ فِي الْمَاءِ فَيُخَلِّلُ بِهَا أُصُولَ شَعَرِهِ ثُمَّ يَصُبُّ عَلَى رَأْسِهِ ثَلَاثَ غُرَفٍ بِيَدَيْهِ ثُمَّ يُفِيضُ الْمَاءَ عَلَى جِلْدِهِ كُلِّهِ
248 صحيح البخاري كتاب الغسل باب الوضوء قبل الغسل
