signs, symptoms and cures of the spiritual diseases of the heart
Ghill is a malady of the heart that is closely related to rancor, extreme anger, and malice. It comes from the same Arabic root from which th word aghla̅l originates, which is used in the Qur'an to mean yokes around the neck (QUR'AN, 36:8), as if to say that rancor dwells in a heart bound to rancor and treachery. Rancor is a pungent emotion that is rooted in being extremely angry at a person to the point that one wishes harm to come to him. But the ultimate victim of rancor is its carrier. For this reason, believers pray, "Our Lord, forgive us and our brethren who came before us in faith, and do not place into our hearts rancor for those who believe! Our Lord, You are kind, compassionate" (QUR'AN, 59:10). One of the great blessings of Paradise is that God will completely remove any semblance of rancor from one's heart (QUR'AN, 7:43, 15:47).
Satan rejoices when believers fight with one another and bear negative thoughts and feelings. There is an authentic hadith about Mondays and Thursdays being special days in which God forgives people. When the angels come to God and say that two believers are wrangling with one another, God, the Exalted, says, "Leave them until they set things aright between themselves." The implication is that if a person has rancor toward another believer, God shall not forgive that person until he forgives his brother, for rancor is a serious affliction that festers in one's heart and blocks good things from coming to one.
Imam Mawlu̅d says that if a person feels rancor toward a particular person, he should show that person goodwill. By nature, people are naturally inclined to love those who do good to them. And if one shows a person good, feelings of rancor will fall to the wayside.