What is the religious ruling on reclaiming a distinctive mobile phone SIM card that a person gifted to a relative, then reclaimed from him due to obsessive-compulsive thoughts and doubts? Is it permissible to use it or conduct financial transactions through it? And does the influence of these obsessive thoughts render a loan for buying a house unlawful?

The cure for obsessive whispers (waswasa) is to turn away from them, not pay attention to them, and to seek refuge in Allah through supplication (du'a). The person afflicted with waswasa is not bound by a divorce [due to it], and whatever whispers come to him are from Satan. Turning away from these whispers makes Satan despair of misleading the afflicted person. As for the matter of the SIM card, it is not permissible to take back a gift; it must be returned to its owner, based on the saying of the Messenger of Allah (peace be upon him): "It is not permissible for anyone to be given a gift and then take it back, except for a father concerning what he gives his child," and his saying (peace be upon him): "The one who takes back his gift is like a dog that vomits and then returns to its vomit."