When the Messenger of Allah (ﷺ) prayed he would Jakhkha.
Sunan an-Nasa'i Book 12, Hadith 77
← Previous Hadith "Al-Bara' described the prostration to us. He places his hands on the ground and raised his posterior and said: 'This is what I saw the Messenger of Allah (ﷺ) doing."

Sunan an-Nasa'i Book 12, Hadith 76 Next Hadith → When the Messenger of Allah (ﷺ) prayed he held his arms out so much that the whiteness of his armpits appeared.

Sunan an-Nasa'i Book 12, Hadith 78