An explanation of the pointing/moving of the finger when in Tashahhud. Taken from Explanation of The Prophet’s Prayer Described of Shaykh Muḥammad Nāṣir al-Dīn Al-Albānī by Shaykh Muḥammad ibn ʿUmar Bazmūl.
It is indeed more powerful against the Shayṭān than iron.
Shaykh al-Albānī said:
He (ṣallallāhu ʿalayhi wa-sallam) would spread his left palm upon his left knee and clench all of the fingers of his right hand, point with the finger adjacent to the thumb towards the qiblah and cast his vision towards it. When he pointed his finger, he would put his thumb upon his middle finger and sometimes he would make a circle with them. When he raised his finger he would move it, supplicating with it, and he would say:
“It is indeed more powerful against the Shayṭān than iron.”
(He said this) referring to the forefinger. And the companions of the Prophet (ṣallallāhu ʿalayhi wa-sallam) would remind each other (i.e. about pointing with the finger when supplicating). And he (ṣallallāhu ʿalayhi wa-sallam) would do this in both Tashahhuds. Once he (ṣallallāhu ʿalayhi wa-sallam) saw a man supplicating with two fingers so he said to him:
And he pointed with his index finger.
Shaykh Muḥammad Bazmūl said:
This chapter contains a number of issues. They are as follows:
The First Issue: Description of the placing the left hand upon the left thigh. He (ṣallallāhu ʿalayhi wa-sallam) would place his left hand upon his left thigh and spread his left palm upon the left knee, clenching the fingers of the left hand.
The Second Issue: The Description of the right palm. As for the right palm, he would place the right hand upon the right thigh, clenching the fingers of the right hand. And in this clenching of the fingers there are two descriptions.
The First Description: That he would join all of the fingers together, with the exception of the index finger, or the finger of testification, which he would extend. So he would grasp all of the fingers, clasping the fingers to the middle of the palm, and would place the thumb upon the middle finger.
The Second Description: is that he would make the fingers just as has preceded except that he would form a circle with the thumb and the middle fingers. This is the second description, for the pinkie and the ring finger would be affixed to the middle of the palm, and the middle finger would be with the thumb, in the form of a circle. And the index finger of testification would be straight such that he would point with it to the direction of the qiblah.
The Third Issue: I say: He (ṣallallāhu ʿalayhi wa-sallam) would point with this finger towards the direction of the qiblah and set his gaze towards it. Meaning: He would look, while pointing, towards this finger. So he would not look towards the place of prostration, nor would he look in front of him. He would only look towards his finger. This is the Sunnah, as it relates to this sitting.
The Fourth Issue: He (ṣallallāhu ʿalayhi wa-sallam) would point with it then move it. And this movement is a very slight movement and does not reach the point of raising it and lowering it as some of the youth do. Nor does it reach the point of a movement to the right or to the left. It is only a very slight movement, this is the meaning of his statement: “…He would move it and supplicate with it.”
The Fifth Issue: The worshipper is to continue pointing and slightly moving his finger all the while he is saying the Tashahhud. This is because the entire Tashahhud is a supplication. The notification has already preceded regarding the fact that supplication is of two types: the supplication of request and asking, and supplication of glorification and magnification. The Tashahhud contains supplication of request and asking and it also contains supplication of magnification and glorification. The meaning of this is that the worshipper throughout the entirety of the Tashahhud is to point and supplicate with his finger and he is not to remove it. So when he completes the supplication then the legislation of pointing with the index finger ends as well.
The Sixth Issue: I say: The Messenger (ṣallallāhu ʿalayhi wa-sallam) clarified the wisdom behind this pointing with the index finger. And it is that it is severe against the Shayṭān. There has come in the ḥadīth which the author has cited: “It is more severe against the Shayṭān than iron, meaning the index finger.” And there has also come on the authority of Ibn ʿUmar, as is within the collection of Al-Humaydee 1/313 as well as Abū Ya’lā and his Musnad 2/275, as is within the footnote of the Prophet’s Prayer Described, “It is the shooting of Shayṭān, no one will forget when he does this.” meaning, when he points with his index finger while saying At-Tashahhud. al-Bayḥaqī reports in Al-Sunan al-Kubrā 2/132: “On the authority of Al-Waaqidee, who said, ‘Kathīr ibn Zayd narrated to us on the authority of Naafi’ from Ibn ʿUmar, that the Prophet (ṣallallāhu ʿalayhi wa-sallam) said: “Moving the finger in the prayer terrifies the Shayṭān.” al-Bayḥaqī said: “Muḥammad Ibn ʿUmar al-Waaqidee was alone in narrating it. And he is not strong. We have narrated from Mujāhid that he said: ‘The man moving his finger when sitting in the prayer is a suppressor for the Shayṭān.’” And he cited the chain of narration after the report of Mujahid 2/133.
The Seventh Issue: This is a Sunnah in the description of the finger, pointing with it and moving it, during the Tashahhud. The companions would remind each other regarding it, meaning they would draw each other’s attention to it.
The Eighth Issue: This supplication and pointing with the finger is only to be done with the right hand and not the left. So one is not to point with the right finger and the left finger, nor is he to point during the Tashahhud with two fingers. He is only to point with one, and that is the right hand and the right index finger, or finger of testification, from the right hand. Due to that, when the Messenger (ṣallallāhu ʿalayhi wa-sallam) saw a man pointing with two fingers he said to him: “One. One.” Meaning with one finger only, not with two fingers nor with two hands, rather with one finger only and with one hand only. And it is the right hand.
The Ninth Issue: Pointing with the finger is an indication of Tawḥīd, due to the statement of the Messenger (ṣallallāhu ʿalayhi wa-sallam): “One. One.” al-Bayḥaqī reported it 2/132, with its chain of narration from Muqsim Abū al-Qāsim. He said: “A man from the people of Madīnah narrated to me saying, ‘I prayed beside Khaffaaf ibn Aymaa’ ibn Rahdah and he saw me pointing with my finger in the prayer so he said, ‘My dear cousin, why do you do this?’ I said, ‘I saw the best of the people and their jurists doing it.’ He said, ‘You are correct. I saw Allāh’s Messenger (ṣallallāhu ʿalayhi wa-sallam) and he used to point with his finger when he sat, saying the Tashahhud within his prayer. And the mushrikūn would say, ‘He is casting a spell on us,’ whereas the Prophet (ṣallallāhu ʿalayhi wa-sallam) only intended At-Tawḥīd.”
Within its chain of narration there is ambiguity. Al-Bāyahqee reported 2/133, with his chain of narration on the authority of Abū ʿIshāʾq, from Al-‘Eezaar, who said: “Ibn ʿAbbās was asked about a man supplicating while pointing with his finger, so Ibn ʿAbbāss said: “It is al-Ikhlās (purity, sincerity).” Also he mentioned, with his chain of narration, on the authority of Ibrāhīm Ibn ʿAbdullāh ibn Ma’bad from Ibn ʿAbbās that Allāh’s Messenger (ṣallallāhu ʿalayhi wa-sallam) said: “This is al-Ikhlās (and he pointed with his finger which is adjacent to the thumb), and this is ad-Duaa’ (and he raised his hands parallel to his shoulders), and this is humble supplication (and he raised his hands and cupped them).”