Maliks Muwatta Book 9, Hadith Number 63.
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 say, “When one of you puts his forehead on the ground he should put his palms on the place where he puts his forehead. Then, when he rises, he should raise them, for the hands prostrate just as the face prostrates.”