Nasai

1271. Commentary: «وَلَا يُحَرِّكُهَا» With the addition of “and he would not move it,” this narration is shaadh (anomalous). Shaykh al-Albani rahimahullah states: The chain of this hadith is hasan (good), but the addition of «وَلَا يُحَرِّكُهَا» is shaadh. Ziyad ibn Sa‘d is alone in narrating this from Ibn ‘Ajlan, and a group of trustworthy narrators have opposed him in this, in that when they narrated this hadith from Ibn ‘Ajlan, they transmitted it without this addition. Two trustworthy narrators have also followed up Ibn ‘Ajlan; they too narrated this from ‘Amir ibn ‘Abdullah without this addition. Therefore, Ibn al-Qayyim rahimahullah said: “Its authenticity is questionable.” Furthermore, this addition is also contradicted by the hadith of Wa’il ibn Hujr radi Allahu anhu, in which it is mentioned that then the Prophet sallallahu alayhi wa sallam raised his finger. I saw him moving it and supplicating with it. For details, see: [ضعیف سنن أبي داود (مفصل) للألباني ، حدیث : 175]. In summary, the aforementioned addition is weak and shaadh, whereas the rest of the hadith reaches the level of acceptance. Although the verifier of the book has declared the entire narration weak in its chain. And Allah knows best.

Benefits and Issues
This hadith is weak:
Because in it, Muhammad bin ‘Ajlan narrates from ‘Amir bin ‘Abdullah bin Zubair, and Muhammad bin ‘Ajlan is a narrator about whom there is criticism. Besides him, four reliable narrators have narrated this same report from ‘Amir bin ‘Abdullah, but the words «لَا يُحَرِّكُهَا» are not present in their narrations.
It is thus evident that these words are anomalous (shadh).
Imam Muslim rahimahullah has also mentioned this narration through the route of Muhammad bin ‘Ajlan, and even in that, the words «لَا يُحَرِّكُهَا» are not present.

989. Commentary:
The narration that does not mention movement is weak in its chain of transmission. However, some scholars have declared it authentic and, reconciling between pointing and not moving, have explained—as Shawkani has transmitted from Imam Bayhaqi—that the Prophet (sallallahu alayhi wa sallam) would point but there would not be repeated movement. See: [نيل اوطار باب الاشاره بالسبابة]

Therefore, if one acts upon both movement and pointing in such a way that, upon sitting for the tashahhud, one forms the knot of counting at 53 and raises the finger, keeping it upright in the state of pointing until the salutation (salam) is given—as this is the manner of the finger in tashahhud as understood from the ahadith—and moves it a few times in between, so that the narration mentioning movement is also acted upon, then this is permissible. However, the repetition and excessive movement, as has become common practice, has no strong basis. «والله اعلم»

Moving the index finger during supplication in Tashahhud
Moving the index finger (continuously) during supplication in Tashahhud is established by authentic hadith. See: [سنن النسائي 1269، و سنده صحيح ابن خزيمه 714 منتقي ابن الجارود 208 اور صحيح ابن حبان الاحسان: 1857]

As for the narration in which it is mentioned that the Prophet sallallahu alayhi wa sallam used to point with his finger and did not move it, see: [سنن ابي داود: 989 اور السنن الكبريٰ للبيهقي 132/2]

Its chain is weak due to the ‘an‘anah of Muhammad ibn ‘Ajlan (a mudallis narrator).

Hafiz Ibn Hajar rahimahullah has mentioned Ibn ‘Ajlan among the third category of mudallisin. See: [الفتح المبين ص60]

Tahawi has also declared Muhammad ibn ‘Ajlan to be a mudallis.

See: [مشكل الآثار طبع قديم ج1 ص100، 101]

It is incorrect to call this weak narration authentic.

Remember that a weak narration is rejected, and reconciliation (tatbiq) is only done where both hadiths are authentic.

... See the original article ...

Fatawa ‘Ilmiyyah (Tawdih al-Ahkam) Vol. 2, p. 77