Sahih Muslim Book 4, Hadith Number 1005.

Chapter : Moderation in prostration, placing the palms on the earth (ground), and keeping away elbows from the sides and the belly from the things while prostrating.

‘Aisha reported: The Messenger of Allah (may peace be upon him) used to begin prayer with takbir (saying Allah-o-Akbar) and the recitation: “Praise be to Allah, the Lord of the Universe.” When he bowed he neither kept his head up nor bent it down, but kept it between these extremes; when he raised his bead after bowing he did not prostrate himself till he had stood erect; when he raised his head after prostration he did not prostrate himself again till he sat-up. At the end of every two rak’ahs he recited the tahiyya; and he used to place his left foot flat (on the ground) and raise up the right; he prohibited the devil’s way of sitting on the heels, and he forbade people to spread out their arms like a wild beast. And he used to finish the prayer with the taslim.