Musannaf Ibn Abi Shayba 3:291

Abu al-Ahwas narrated to us, from ‘Ata’ ibn al-Sa’ib, from Salim al-Barrad, who said: We came to Abu Mas’ud al-Ansari in his house and said, "Teach us the prayer of the Messenger of Allah, may Allah bless him and grant him peace." So he prayed, and when he prostrated, he placed his palms close to his head.