(51) باب صِفَةِ السُّجُودِ
It was narrated that Abu Hurairah said:
"If I were in front of the Messenger of Allah (ﷺ) I would be able to see the whiteness of his armpits." (One of the narrators) Abu Mijlaz said: "It is as if he said that because he was praying."
Reference: Sunan an-Nasa'i 1107
In-book reference: Book 12, Hadith 79
English translation: Vol. 2, Book 12, Hadith 1108