He saw the Messenger of Allah (ﷺ) doing like this.
Sahih Muslim Book 4, Hadith 320
← Previous Hadith I called upon the Messenger of Allah (ﷺ)."

Sahih Muslim Book 4, Hadith 319 Next Hadith → I visited the Apostle (ﷺ) and saw him praying on a reed mat on which he was prostrating himself. And I saw him praying in a single garment with ends crossed with each other.

Sahih Muslim Book 4, Hadith 321