How can one advise a person on the necessity of sincere inner forgiveness from the heart towards people and patience with their harm, and not merely outward forgiveness?

A Muslim loves for his brother what he loves for himself, and dislikes for him what he dislikes for himself. This includes forgiveness and pardon. Allah Almighty has encouraged forgiveness and patience in the face of harm, saying: "And those who restrain anger and pardon people—and Allah loves the doers of good." A Muslim loves for people to overlook his faults, and he is in dire need of his good deeds on the Day of Resurrection. For this reason, Allah encouraged Abu Bakr to forgive Mistah, saying: "And let them pardon and overlook. Would you not like that Allah should forgive you? And Allah is Forgiving and Merciful." Allah has promised that whoever pardons and reconciles, his reward is with Allah, and recompense is of the same kind as the deed. Among the greatest things that help achieve a sound heart are sincerity in action for the sake of Allah, advising the leaders of the Muslims, adhering to their community, and for a person to be "pure of heart," which means being pious and pure, free from sin, wrongdoing, malice, or envy.