signs, symptoms and cures of the spiritual diseases of the heart
A strong dislike of a person for no legitimate reason is the disease of hatred. In itself, hatred is not necessarily negative. It is commendable to hate corruption, evil, disbelief, murder, lewdness, and anything else that God has exposed as despicable.
Absence of love. Love is an attribute of God; hate is not.
One should pray for the person toward whom he feels hatred, making specific supplications that mention 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.
Hate is absence of love, and only through love can hatred be removed from the heart.
The Prophet ﷺ said: "None of you has achieved faith until he loves for his brother what he loves for himself." The thirteenth century scholar Imam al-Nawawi comments on this hadith:
When the Prophet ﷺ says, "brother", we should interpret this as universal brotherhood, which includes Muslims and non-Muslims. For one should desire for his brother non-Muslim that he enter into the state of submission with his Lord [Islam]. And for his brother Muslim, he should love for him the continuation of guidance and that he remain in submission. Because of this, it is considered highly recommended and divinely rewarding to pray for a non-Muslim's guidance. The word "love" here refers to a desire for good and for benefit to come to others. This love is celestial or spiritual love and not earthly or human love, for human nature causes people to desire harm to befall their enemies and to discriminate against those who are unlike them [in creed, color, or character]. However, men must oppose their nature, pray for their brothers, and desire for others what they desire for themselves. Moreover, whenever a man does not desire good for his brother, envy is the root cause. Envy is a rejection of God's apportionment in the world. Thus, one is opposing how God meted out sustenance in accord with His wisdom. Therefore, one must oppose his own ego's desires and seek treatment for this disease with the healing force of acceptance of the divine decree and prayer on behalf of one's enemies in a way that suppresses the ego [nafs]