Sunan Ibn Majah Book 5, Hadith 80
“I saw the Prophet (ﷺ)
when
he prostrated and put his knees on the ground before his hands,
and
when he stood up after prostrating, he took his hands off the
ground
before his knees.”
“I was with my father on the plain in Namirah,* 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 came, (i.e., I came near,) then there was the Messenger of Allah (ﷺ), and 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 (ﷺ) every time he prostrated.”
Ibn Majah said: The people say `Ubaidullah 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 `Ubaidullah bin `Abdullah bin Aqram, from his father, from the Prophet (ﷺ).'" With similar wording.
“I have been commanded to prostrate on seven bones.”