(27) باب يُبْدِي ضَبْعَيْهِ وَيُجَافِي فِي السُّجُودِ
Narrated 'Abdullah bin Malik:
Ibn Buhaina, "When the Prophet (ﷺ) prayed, he used to separate his arms from his body so widely that the whiteness of his armpits was visible."
Reference: Sahih al-Bukhari 390
In-book reference: Book 8, Hadith 42
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 1, Book 8, Hadith 385