" The cure for hatred is straightforward. One should pray for the person toward whom he feels hatred; make specific supplication mentioning this person by name, asking God to give this person good things in this life and the next. When one does this with sincerity, hearts mend.
If one truly wants to purify his or her heart and root out disease, there must be total sincerity and conviction that these cures are effective.. "

― , Purification of the Heart: Signs, Symptoms and Cures of the Spiritual Diseases of the Heart