Salam alaikum,is there a hadith that says,that if someone reverted to islam and while he is saying his shadah to Allah he must point his index fingerlike the way we are doing in our prayer while in tashahud, and also is it haram to wear a ring on that finger.?jazaka Allahum khair

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu 'alyhi wa sallam, is His slave and Messenger.

We are not aware of any Hadeeth which states that when a person embraces Islam, he should point with his index finger when uttering the Two Testimonies of Faith (which is to say, "Ash-hadu allaa ilaaha illallaah wa ash-hadu anna Muhammadan rasoolallaah." I testify that none has the right to be worshipped but Allaah and I testify that Muhammad is the Messenger of Allaah), and no scholar has ever said this.

Also, a woman may wear a ring on any of her fingers. Whereas the Sunnah for a man is to wear a ring on his pinkie of his left hand and he is not permitted to wear a ring in his index or middle fingers. 'Ali narrated, “The Prophet prohibited me from wearing a ring on my index and middle fingers.” [Muslim]

However, there is a difference of opinion among the scholars on wearing a ring on the thumb.

For further details, please refer to Fatwas 89085 and 83926.

Allaah Knows best.