Moving the Finger in Tashahhud
I have heard that drawing the thumb against the middle finger and extending the forefinger and moving it is harsher for the devil then being struck with iron ... to what extent is this narration correct?
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.
Shaykh Muhammad bin Saalih al-`Uthaymeen
Fatawa Islamiyah Vol. 2 Page 208