Sahih Muslim Book 4, Hadith Number 1204.

Chapter : Prostration while reciting the Qur’an.

‘Ali b. ‘Abual-Rahman al-Mu’awi reported: ‘Abdullah b. Umar saw me playing with pebbles during prayer. After finishing the prayer he forbade me (to do it) and said: Do as the Messenger of Allah (may peace be upon him) used to do. I said: How did Allah’s Messenger (may peace be upon him) do? He said that he (the Messenger of Allah) sat at tashahhud, placed his right palm on the right thigh and closed all his fingers and pointed with the help of finger next to the thumb, and placed his left palm on his right thigh.