The Book of Prayers
4/46. Chapter:
The Description Of The Prayer, With What It Begins And Ends. The Description Of Bowing And Moderation Therein, And Of Prostration And Moderation Therein. Tashah-hud After Each Two Rak'ah Of Four Rak'ah Prayers. Description Ol Sitting Between The Two Prostrations, And In The First Tashah-hud
Sahih Muslim
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَعَمْرٌو النَّاقِدُ، وَزُهَيْرُ بْنُ حَرْبٍ، وَإِسْحَاقُ بْنُ إِبْرَاهِيمَ، - وَاللَّفْظُ لِعَمْرٍو - قَالَ إِسْحَاقُ أَخْبَرَنَا وَقَالَ الآخَرُونَ، حَدَّثَنَا وَكِيعٌ، حَدَّثَنَا جَعْفَرُ بْنُ بُرْقَانَ، عَنْ يَزِيدَ بْنِ الأَصَمِّ، عَنْ مَيْمُونَةَ بِنْتِ الْحَارِثِ، قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم إِذَا سَجَدَ جَافَى حَتَّى يَرَى مَنْ خَلْفَهُ وَضَحَ إِبْطَيْهِ . قَالَ وَكِيعٌ يَعْنِي بَيَاضَهُمَا .
Maimuna daughter of Harith reported: When the Messenger of Allah (ﷺ) prostrated, he kept his hands so much apart from each other that when it was seen from behind the armpits became visible. Waki' said: That is their whiteness.
Reference : Sahih Muslim 497bIn-book reference : Book 4, Hadith 271USC-MSA web (English) reference : Book 4, Hadith 1004