Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: It was said: "O Messenger of Allah, which (form of) Islam is best?" He (peace and blessings be upon him) said: "The gentle and easy Hanifiyyah (pure monotheism)."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11522