Reference: Fataawa Mu’aasirah – Page 393
Question: Noble Shaykh may Allaah forgive you [your sins]. What is your opinion regarding the moving of the index finger whilst supplicating during the sitting [of rest] between the two prostrations in the prayer?
Response: That which I am of the opinion is that it is a Sunnah, based upon the hadeeth of Waa.il ibn Hajar [transmitted by Abu Daawood and Ibn Khuzaymah and Ibn Hibbaan] [as occurs] in the Musnad of Imaam Ahmad, and it has been authenticated by Ibn Khuzaymah and Ibn Hibbaan and as-Saa’aatee in the Musnad of Imaam Ahmad, and he said regarding it: “Indeed its chain of transmission is good”. He said this in al-Fat.h ar-Rabbaanee and al-Arnaa.oot [mentioned it] in Zaad al-Ma’aad.
And therein is the permissibility of placing the right hand [on the right thigh] between the two prostrations just as it is placed [likewise] during the tashahhud. And I have a reference for this from the people of knowledge, [namely] Ibn al-Qayyim as occurs in Zaad al-Ma’aad. And he has was clear about placing the two hands [on their respective thighs] between the two prostrations just as they are placed [likewise] during the tashahhud. It is then said that there is nothing mentioned on the authority of the Prophet (sal-Allaahu ‘alayhi wa sallam) that he placed his right hand on his [right] thigh [by the knee] opened out, as for the left [hand] then the Sunnah is clear in that regard that it is placed on the thigh opened out on the thigh [by the knee] – all of that is permissible. And these are two manners/ways, however, there is a point [of note], when do we indicate with the right [index] finger, [is it] continuously whilst sitting during the tashahhud or [whilst] resting between the two prostrations?
And the answer: That which has reached me from the Sunnah is that one indicates with it whilst supplicating, so a person moves it [pointing with it] upwards while he supplicates. And the appropriateness for this is that the supplication is directed towards Allaah (‘Azza wa Jall) which is an indication of His Loftiness [above all of His creation], and this is what is apparent to me regarding this [whole] issue.