It wasnarrated from (`Ubaidullah bin `Abdullah) bin Aqram Al-Khuza`ithat his father said:
"I was with my father on the plain inNamirah,*when some riders passed us and made their camels kneel downat theside of the road. My father said to me: 'Stay with yourlambs until Igo to those people and see what they want.' He said:Then he (myfather) went out and I came, (i.e., I came near,) thenthere was theMessenger of Allah (ﷺ), and the time for prayer cameso I prayedwith them, and I was looking at the whiteness of thearmpits of theMessenger 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.
English reference: Vol. 1, Book 5, Hadith 881
Arabic reference: Book 5, Hadith 930