Abdullah bin Malik reported,

When the Messenger of Allah ﷺ prayed, he would hold his arms away from his sides until the whiteness of his armpits became visible.

Muslim 1105

Sahih

حدثنا قتيبة بن سعيد حدثنا بكر وهو ابن مضر عن جعفر بن ربيعة عن الأعرج

عن عبد الله بن مالك ابن بحينة

أن رسول الله ﷺ كان إذا صلى فرج بين يديه حتى يبدو بياض إبطيه

مسلم 1105صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Muslim
Book
Prayer
Chapter
What encompasses the description of prayer, how it is opened and concluded, the description of ruku and rising from it, sujud and rising from it, the tashahhud after every two rakahs in a four-rakah prayer, and the description of sitting between the two prostrations and in the first tashahhud
Numbering
Darussalam 1105
Muslim 1105