Sayyiduna Abu Hurayrah (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "Whoever loves them both has loved me, and whoever hates them has hated me," meaning Hasan and Husayn.
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2633