CHAPTER: What Has Been Reported About Swearing That One Has Nothing To Do With Islam Or That One Belongs To Another Religion.
Narrated Thabit bin Adh-Dahhak: That he took oath of allegiance to the Messenger of Allah صلی اللہ علیہ وسلم under the tree. The Messenger of Allah صلی اللہ علیہ وسلم said: If anyone swears by religion other than Islam falsely, he is like what has has said. If anyone kills himself with something, he will be punished with it on the Day of Resurrection. A vow over which a man has no control is not binding on him.
Narrated Buraydah ibn al-Hasib: The Prophet صلی اللہ علیہ وسلم said: If anyone takes an oath and says: I am free from Islam; now if he is a liar (in his oath), he will not return to Islam with soundness.