It is narrated from Umm al-Mu'mineen Aisha (may Allah be pleased with her) that she said: When the Messenger of Allah (ﷺ) intended to perform ghusl after janabah, he would wash his hands before putting them into the vessel, then wash his private parts, then perform wudu as for prayer, then wet his hair with water, then pour three handfuls of water over his head.
Hadith Referenceمسند الإمام الشافعي / كتاب الطهارة / 104
Hadith Takhrijاخرجہ البخاری: الغسل، باب تخليل الشعر، حتى اذا ظن أنه قد اروى بشرته افاض علیه (272) - ومسلم، الحيض، باب صفة غسل الجنابة (316)