Some of the ma'mum (those praying behind the imam) raise their index finger when the imam recites the Qur'an and Allah is mentioned. Is this prescribed?

Question:
Honorable Shaykh, may Allah grant you success. He says: Some of the ma'mum raise their index finger when the imam recites the Qur'an and Allah is mentioned. Is this prescribed?

Answer:
I do not know of any basis for this. Raising the index finger is prescribed during the tashahhud and during supplication as a sign of tawhid (the oneness of Allah). Apart from that, it is not prescribed to raise the index finger.