Nahj al-Balagha Hadith n. 268

Selections from The Sayings and Preaching of Amir al-Muminin Ali ibn Abi Talib (Peace Be Upon Him) Including His Replies to Questions and Maxims Expressed for Various Purposes.
Translated by Sayyid Ali Reza

وَقَالَ (عليه ‏السلام):

Amir al-mu'minin, peace be upon him, said:

أَحْبِبْ حَبِيبَكَ هَوْناً مَا عَسَى أَنْ يَكُونَ بَغِيضَكَ يَوْماً مَا،

Have love for your friend up to a limit, for it is possible that he may turn into your enemy some day;

وَأَبْغِضْ بَغِيضَكَ هَوْناً مَا عَسَى أَنْ يَكُونَ حَبِيبَكَ يَوْماً مَا.

and hate your enemy up to a limit for it is possible that he may turn into your friend some day.