Abdullah ibn Hunayn continued, "Abdullah ibn Abbas sent me to Abu Ayyub al-Ansari, and I found him doing ghusl between the posts of a well, screened by a garment. I greeted him and hesaid, 'Who is that?' I replied, 'I am 'Abdullah ibn Hunayn. 'Abdullah ibn Abbas sent me to you to ask how the Messenger of Allah (ﷺ) used to wash his head when he was in ihram.' "
He continued, "Abu Ayyub put his hand on the garment and pulled it down until I could see his head. He said to the man who was pouring out the water for him, 'Pour,' and he poured some over his head. Then he passed his hands over his head from the front to the back and then to the front again, and then said, 'I saw the Messenger of Allah (ﷺ) doing it like this.' "
Arabic : Book 20, Hadith 711