From that link: "Shahada is mentioned after "Allahu Akbar" and at the end of prayer. It is done with first finger of right hand extended as a witness to the unity of Allah."
The finger gesture is a sort of shorthand to the faithful.
20 posted on 11/29/2015 10:33:46 PM PST by Smokin' Joe
(How often God must weep at humans' folly. Stand fast. God knows what He is doing.)