Maliks Muwatta Book 9, Hadith Number 62.
Section : Placing the Hands Flat on the Surface by the Face when Prostrating.
Yahya related to me from Malik from Nafi that Abdullah ibn Umar used to place his palms flat on the surface where he put his forehead. Nafi said, “I have seen him take his hands out from under his burnus on a very cold day and place them on the ground.”