Is a Muslim rewarded for forgiving a non-Muslim who wronged him, and is it better to forgive both a Muslim and a non-Muslim, or only a Muslim, taking into account that forgiving a non-Muslim might lead to missing an opportunity to take some of their sins?

It is permissible to forgive disbelievers and show them leniency, especially if there is hope that they might be guided and influenced by the ethics of Islam, for Allah commanded His Prophet to overlook their faults. The oppressor is warned that his good deeds will be taken for the oppressed; and if he has no good deeds, then some of the oppressed person's sins will be taken and cast upon him, after which he will be thrown into the Fire. Disbelievers have no good deeds, and there is no evidence to prevent taking the sins of the oppressed and casting them upon them.