Sunan an Nasai
1147
Sahih+2

It was narrated that Maimunah said:"When the Messenger of Allah (ﷺ) prostrated, he would hold his arms out to his sides, so that the whiteness of his armpits could be seen from behind. And when he sat he rested on his left thigh

SahihAbu Ghuddah
SahihAl-Albani