Sunan Ibn Majah Book 25, Hadith 53
“Who is this?” I said: “I am ‘Abdullah bin Hunain. ‘Abdullah bin ‘Abbas sent me to you to ask you how the Messenger of Allah (ﷺ) used to wash his head when he was in Ihram.” He said: “Abu Ayyub put his hand on the cloth and lowered it until his head appeared, then he said to someone who was pouring water for him, Pour water. So he poured water on his head. Then he rubbed his head with his hands, forwards and backwards, and said: ‘This is what I saw him (ﷺ) doing.’”
“We went out with the Messenger of Allah (ﷺ) until, when we were in ‘Arj, we stopped to camp. The Messenger of Allah (ﷺ) sat, with ‘Aishah by his side, and I was sitting beside Abu Bakr. Our mount* and the mount of Abu Bakr was one, under the care of the slave of Abu Bakr. The slave looked and his camel was not with him, so he said to him: ‘Where is your camel?’ He said: ‘I lost it yesterday.’ He said: ‘You have one camel with you and you lost it?’ He started to beat him, and the Messenger of Allah (ﷺ) said: ‘Look at what this Muhrim is doing!’”
“We were with the Prophet (ﷺ), and we were in Ihram. When a rider met us we would lower our garments from the top of our heads, and when he has gone, we would lift them up again.”
Another chain reports a similar hadith.