1113An NasaiSahih (Darussalam)أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا بَكْرٌ، عَنْ جَعْفَرِ بْنِ رَبِيعَةَ، عَنِ الأَعْرَجِ، عَنْ عَبْدِ اللَّهِ بْنِ مَالِكِ ابْنِ بُحَيْنَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ إِذَا صَلَّى فَرَّجَ بَيْنَ يَدَيْهِ حَتَّى يَبْدُوَ بَيَاضُ إِبْطَيْهِ .It was narrated from Abdullah bin Malik bin Buhainah that:When the Messenger of Allah (ﷺ) prayed he held his arms out so much that the whiteness of his armpits appeared.Reference: Sunan an-Nasa'i 1106 In-book : Book 12, Hadith 78 English translation : Vol. 2, Book 12, Hadith 1107