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 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.

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا وَكِيعٌ، عَنْ دَاوُدَ بْنِ قَيْسٍ، عَنْ عَبْدِ اللَّهِ بْنِ عُبَيْدِ اللَّهِ بْنِ أَقْرَمَ الْخُزَاعِيِّ، عَنْ أَبِيهِ، قَالَ كُنْتُ مَعَ أَبِي بِالْقَاعِ مِنْ نَمِرَةَ فَمَرَّ بِنَا رَكْبٌ فَأَنَاخُوا بِنَاحِيَةِ الطَّرِيقِ فَقَالَ لِي أَبِي كُنْ فِي بَهْمِكَ حَتَّى آتِيَ هَؤُلاَءِ الْقَوْمَ فَأُسَائِلَهُمْ . قَالَ فَخَرَجَ وَجِئْتُ - يَعْنِي دَنَوْتُ - فَإِذَا رَسُولُ اللَّهِ ﷺ فَحَضَرْتُ الصَّلاَةَ فَصَلَّيْتُ مَعَهُمْ فَكُنْتُ أَنْظُرُ إِلَى عُفْرَتَىْ إِبْطَىْ رَسُولِ اللَّهِ ﷺ كُلَّمَا سَجَدَ . قَالَ ابْنُ مَاجَهْ النَّاسُ يَقُولُونَ عُبَيْدُ اللَّهِ بْنُ عَبْدِ اللَّهِ وَقَالَ أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ يَقُولُ النَّاسُ عَبْدُ اللَّهِ بْنُ عُبَيْدِ اللَّهِ . حَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ مَهْدِيٍّ، وَصَفْوَانُ بْنُ عِيسَى، وَأَبُو دَاوُدَ قَالُوا حَدَّثَنَا دَاوُدُ بْنُ قَيْسٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ بْنِ أَقْرَمَ، عَنْ أَبِيهِ، عَنِ النَّبِيِّ ﷺ نَحْوَهُ .