What is the Sunnah regarding moving the index finger during the tashahhud

Q: From E. H. A. - Dammam, I observe that during the recitation of the tashahhud, some of the worshippers move their index finger to the right and left, and some move it up and down, with rapid consecutive movements or slow ones. Others raise their finger and do not move it, and still others do not raise their finger at all. What is the ruling on this?

A: It is a recommended practice (sunnah) for the worshipper during the tashahhud to clasp all his fingers, meaning the fingers of his right hand, and to point with his index finger, moving it slightly during supplication as a sign of the oneness of Allah (tawhid). If he wishes, he may clasp his little finger and ring finger, and loop his thumb around his middle finger, pointing with his index finger. Both of these descriptions are authentic from the Prophet (peace and blessings be upon him). As for his left hand, he places it on his left thigh, with his fingers extended toward the qiblah. If he wishes, he may place it on his knee. Both of these descriptions are authentic from the Prophet (peace and blessings be upon him).