This is a well proven hadith in Sunni School of Thought. This is mentioned in Sahih Muslim and other books of hadith that loving Imam Ali(as) is the symbol of faith and hating the Imam is a sign of hypocrisy.
English Translation:
Ali ibn Abi Talib said:
I swear to Allah who cracked seed and created the life surely the Holy Prophet advised about me nobody will love me but a believer and nobody will have hatred about me but hypocrite.
Another Narration
English Translation:
Zar bin Habish narrated:
Ali ibn Abi Talib said “Surely the Holy Prophet advised about me that only a believer will love me and the person who is hypocrite will hate me.”
