Is an expiation [kaffarah] obligatory for a 26-year-old young man who imitated a girl's voice over the phone to a friend, which led to the friend masturbating, to the best of the young man's knowledge? And what is incumbent upon him to do?

A man is not permitted to imitate a woman's voice, as this constitutes the forbidden act of imitation (tashabbuh). Its prohibition intensifies if the intention behind it is to arouse lust or to corrupt another person's worship. The perpetrator of such an act is not required to offer expiation (kaffarah). Whoever commits this must seek Allah's forgiveness (istighfar) and offer sincere repentance (tawbah nasuhah), which entails immediately abandoning the sin, regretting it, and resolving never to return to it. It is also advisable to utilize time for beneficial pursuits, associate with the righteous, and keep away from the wicked.