Sahih Muslim Book 4, Hadith Number 1203.

Chapter : Prostration while reciting the Qur’an.

Ibn ‘Umar reported that when the Messenger of Allah (may peace be upon him) sat for tashahhud he placed his left hand on his left knee and his right hand on his right knee and he raised his right finger, which is next to the thumb, making supplication in this way, and he stretched his left hand on his left knee. Another version on the authority of Ibn Umar says: When the Messenger of Allah (may peace be upon him) sat for tashahhud, he placed his left hand on his left knee and placed his right hand on his right knee, and he formed a ring like (fifty-three) and pointed with his finger of attestation.