First of all, we’d like to state that a Muslim should concern himself with maintaining Khushu` (concentration) at prayer. The issue of moving the index finger or not moving it is neither a pillar nor an obligatory act of prayer, so it may be done in any way.
In his well-known book, Fiqh As-Sunnah, Sheikh Sayyed Sabiq states:
“One should sit for the Tashahhud and place his hands in the following manner:
1- Ibn `Umar reported that when the Prophet sat for the Tashahhud, he would place his left hand on his left knee and his right hand upon his right knee, and he would form a ring and point with his index finger. In another narration it is reported, “He would close his hand and point with his index finger.” (Reported by Muslim.)
2- Wa’il ibn Hajar reported that the Prophet would place his left palm on his left thigh and knee. He would place the end of his right elbow upon his right thigh and would then close his right hand, forming a circle. In another narration it states, “He would make a circle with his middle finger and thumb and point with his index finger. Then he would raise his finger, and (Wa’il) saw him moving it to make supplications.” (Reported by Ahmad) Explaining the Hadith, al-Baihaqi says, “The implication of ‘he would move it’ is that he would point with it, not that he would continue to move it.” This would be in agreement with the narration of Ibn az-Zubair who reported, “The Prophet would point with his finger while supplicating, and he would not move it.” This is reported by Abu Dawud with an authentic (Sahih) chain of transmitters. An-Nawawi also mentioned it.
3- Az-Zubair reported, “When the Prophet sat for Tashahhud, he would place his right hand on his right thigh and his left hand on his left thigh. He would point with his middle finger, and would not look beyond his pointing.” (Reported by Ahmad, Muslim and an-Nasa’i.) This hadith shows that one is to place the right hand on the right thigh without closing the hand (making a fist), and that he is not to look beyond his pointing.
The preceding three Hadiths are all authentic, and one may act by any of them.
One should point with one’s right index finger, bending it a little, until one says the salaams at the end of the prayer. Reported Numair al-Khaza’i, “I saw the Messenger of Allah sitting in the prayer with his forearm along his right thigh. His index finger was raised, curved (or bent) a little, and he was supplicating.” (Reported by Ahmad, Abu Dawud, an-Nasa’i, Ibn Majah and Ibn Khuzaimah with a good chain)
Anas ibn Malik said, “The Messenger of Allah, peace and blessings be upon him, passed by Sa`d while he was making supplications (and using) two fingers. The Prophet said to him, ‘Just one, Sa`d’.” (Reported by Ahmad, Abu Dawud, an-Nasa’i and al-Hakim)
Ibn `Abbas was asked about a man who used to point his finger while supplicating, and he said, “This is sincere devotion.”
According to the Shafi`is, one points the finger only once, when saying “but Allah” in the statement bearing witness (i.e. there is no god but Allah). The Hanafis raise the finger in the denial part of the statement (there is no god) and put it back down during the confirmation part (but Allah). The Malikis move the finger to the left and right until they finish the prayer. The Hanbalis point the finger every time they mention Allah, as a reflection of the Oneness of Allah, and they do not move it.”
In conclusion, Sheikh `Atiyyah Saqr, former head of Al-Azhar Fatwa Committee, comments: “Moving the index finger or not moving it is neither a pillar nor an obligatory act of prayer, so it may be done in any way. What is important is to maintain Khushu` in our prayers and perform the pillars and obligatory acts for these are the decisive matters in accepting the prayer.”