Sayyiduna Abu Hurayrah (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say about Hasan and Husayn: "Whoever loves them, it is because of love for me; and whoever hates them, it is because of hatred for me."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2636