It was narrated from ('Ubaidullah bin 'Abdullah) bin Aqram Al-Khuza'i that his father said: "I was with my father on the plain in Namiraha when some riders passed us and made their camels kneel down at the side of the road. My father said to me: 'Stay with your lambs until I go to those people and see what they want.' He said: Then he (my father) went out and I come, (i.e, I came near.) then there was the Messenger of Allah P.B.U.Hand the time for prayer came so I prayed with them, and I was looking at the whiteness of the armpits of the Messenger of Allah P.B.U.H every time he prostrated." (Sahih) Ibn Majah said: The people say 'Ubdaidullah bin 'Abdullah, but Abu Bakr bin Abu Shaibah said: "The people say ,Abdullah bin 'Ubaidullah." Muhammad bin Bashshar said: "Abdur-Rahman bin Mahdi, Safwan bin ' Eisa and Abu Dawud all said: 'Dawud bin Qais narrated to us, from "Ubaidullfih bin' Abdullah bin Aqram, from his father, from the
Prophet 'P.B.U.H with similar wording. (Sahih)