It was narrated from Maimunah that when the Prophet ﷺ prostrated, he would hold his forearms away from his sides, such that if a lamb wanted to pass under his arms, it would be able to do so.  

أَنَّ النَّبِيَّ ﷺ كَانَ إِذَا سَجَدَ جَافَى يَدَيْهِ فَلَوْ أَنَّ بَهْمَةً أَرَادَتْ أَنْ تَمُرَّ بَيْنَ يَدَيْهِ لَمَرَّتْ  

“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 ʿUbaidullah bin ʿAbdullah, but Abu Bakr bin Abu Shaibah said: "The people say ʿAbdullah bin ʿUbaidullah." Muhammad bin Bashshar said: "ʿAbdur-Rahman bin Mahdi, Safwan bin ʿEisa and Abu Dawud all said: 'Dawud bin Qais narrated to us, from ʿUbaidullah bin ʿAbdullah bin Aqram, from his father, from the Prophet ﷺ.'" With similar wording.  

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  

“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.”  

رَأَيْتُ النَّبِيَّ ﷺ إِذَا سَجَدَ وَضَعَ رُكْبَتَيْهِ قَبْلَ يَدَيْهِ وَإِذَا قَامَ مِنَ السُّجُودِ رَفَعَ يَدَيْهِ قَبْلَ رُكْبَتَيْهِ  

“I have been commanded to prostrate on seven bones.”  

عَنِ النَّبِيِّ ﷺ قَالَ أُمِرْتُ أَنْ أَسْجُدَ عَلَى سَبْعَةِ أَعْظُمٍ  

The Messenger of Allah ﷺ said: “I have been commanded to prostrate on seven, but not to tuck up my hair or my garment.”  

رَسُولُ اللَّهِ ﷺ أُمِرْتُ أَنْ أَسْجُدَ عَلَى سَبْعٍ وَلاَ أَكُفَّ شَعَرًا وَلاَ ثَوْبًا قَالَ ابْنُ طَاوُسٍ فَكَانَ أَبِي يَقُولُ الْيَدَيْنِ وَالرُّكْبَتَيْنِ وَالْقَدَمَيْنِ وَكَانَ يَعُدُّ الْجَبْهَةَ وَالأَنْفَ وَاحِدًا  

“When a person prostrates, seven parts of his body prostrate with him: His face, his two hands, his two knees, and his two feet.”  

أَنَّهُ سَمِعَ النَّبِيَّ ﷺ يَقُولُ إِذَا سَجَدَ الْعَبْدُ سَجَدَ مَعَهُ سَبْعَةُ آرَابٍ وَجْهُهُ وَكَفَّاهُ وَرُكْبَتَاهُ وَقَدَمَاهُ  

“We used to feel sorry for the Messenger of Allah ﷺ because he took pains to keep his arms away from his sides when he prostrated.”  

حَدَّثَنَا أَحْمَرُ صَاحِبُ رَسُولِ اللَّهِ ﷺ قَالَ إِنْ كُنَّا لَنَأْوِي لِرَسُولِ اللَّهِ ﷺ مِمَّا يُجَافِي بِيَدَيْهِ عَنْ جَنْبَيْهِ إِذَا سَجَدَ