Moving the Finger in Tashahhud
Question :
I have heard that drawing the thumb against the middle finger and extending the forefinger and moving it is harsher for the devil than being struck with iron ... to what extent is this narration correct?
Answer:
I do not know anything of this narration, but it is lawful for a person to clench the little finger and the ring finger and to make a circle with the thumb and the middle finger and to point with the middle finger while he is supplicating.
Source:
Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 2 Pages 208-209