Is repentance for past ill-will sufficient, or is it necessary to seek forgiveness from those against whom ill-will was harbored?

"Having a bad opinion ( Su' adh-dhann) of Muslims is forbidden by Islamic law, and there are prohibitions against it in the Quran and Sunnah. It leads to many evils such as spying and backbiting. However, fleeting thoughts and inner monologues are excused. The forbidden type of suspicion is that which the soul settles upon and the heart inclines towards.

The forbidden Su' adh-dhann is that which has no sound indication or apparent reason, especially if the person suspected is known for their piety and righteousness. As for repentance from Su' adh-dhann, it is achieved through remorse, abandoning this action, and resolving not to return to it. There is no need to inform the person about whom one had a bad opinion; seeking forgiveness and supplicating for them is sufficient."