It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "By Him in Whose hand is my soul, you cannot enter Paradise until you accept Islam, and you cannot be (true) Muslims until you love one another. Spread the greeting of peace among yourselves, you will love one another. And beware of hatred and enmity, for it is the shaver. I do not say that it shaves hair, but it shaves the religion." It is also narrated in a similar manner from Ibrahim bin Asid through another chain.
Hadith Referenceالادب المفرد / كتاب / 260
Hadith Gradingالألبانی:حسن لغيره
Hadith Takhrij«حسن لغيره : أخرجه الترمذي ، الاستئذان : 2688 و مسلم ، الايمان ، باب بيان أنه لا يدخل الجنة إلا المؤمنون : 154 و أحمد : 1430 و الطيالسي : 190»