Sayyiduna Wa'il bin Hujr (may Allah be pleased with him) said: I prayed with the Messenger of Allah (peace and blessings be upon him). When he (peace and blessings be upon him) said the takbir, he raised his hands; when he intended to bow, he raised his hands; and when he intended to prostrate, he raised his hands. And when he sat for the tashahhud, he would point with his index finger.
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18309