Al-Adab Al-Mufrad #1325
Anger
'Ali was heard to say to Ibn al-Kawwa', "Do you know what the
first one said? 'Loving the one you love is an easy matter. It may be that
one day he will be the one you hate. Hating the one who hate is an easy
matter, It may be that one day he will be the one you hate.'"
About Al-Adab Al-Mufrad
This hadith is #1325 from Al-Adab Al-Mufrad, in the Book of Anger. Al-Adab Al-Mufrad contains 1,326 hadiths across 57 books.