Being An Excerpt from Abu Naasir's Article on 'Dirty Fighting'
Ali bin Abi Talib - radiya Allahu anhu - advised one of his students, Ibn al-Kawwa, he said:
"Love the one you love in measure. It may be that one day he may be the one you hate. Hate the one you hate in measure. He may become beloved to you one day." (Al-Adab al-Mufrad 1321).
A similar counsel by the Messenger of Allah (sallallahu alayhi wasallam) given to Ali bin Abi Talib - radiya Allahu anhu - himself was graded authentic by Shaykh al-Albani.
Explaining these great counsels, al-Imam Ibn al-Atheer said:
"That is, do not go overboard regarding love and hatred, perhaps the loved one may turn a hated person, or that the hated one becomes a beloved. Hence, you would not have gone overboard in loving and then begin to regret or (overboard) in hatred and then you begin to shy about."
Al-Imam Hasan Al-Basriy was a noble Tabi', may Allah shower blessings on him, he was reported to have cautioned too:
"Love in measure and show hatred in measure. Some went to extremes in love for some others and they were ruined; and some were extreme in hatred for some people and became ruined." (Sharh Sahih al-Adab al-Mufrad 3/408).
The leader of the believers, 'Umar bin al-Khattab - radiya Allahu anhu - once told Zayd bin Aslam:
"Do not let your love be total infatuation. Do not let your anger be destruction." Aslam asked how that can be and 'Umar explained, "That is when you love, you are infatuated like a child, and when you hate, you desire your companion's destruction." (Al-Adab al-Mufrad 1322).
Al-Imam Al-Bukhari - rahimahullah - has placed the above narration from 'Umar bin al-Khattab under the chapter heading, "Do Not Let Your Anger Be Destruction."
Moderate your emotions.