Concerning the fact that no one will enter paradise except believers…

Abu Huraira reported: The Messenger of Allaah (may peace and blessing be upon him) observed: You shall not enter Paradise so long as you do not affirm belief (in all those things which are the articles of faith) and you will not believe as long as you do not love one another. Should I not direct you to a thing which, if you do, will foster love amongst you: (i. e.) give currency to (the practice of paying salutation to one another by saying) as-salamu alaikum. (Muslim)

Lessons to learn from this hadith:

1. Iman is a sees planted in the heart. It is not enough for us to know Allah in our heart. But our actions should reflect it. We should attest our faith within our heart, actions and with our limbs.
2. We cannot attain perfection in faith, unless we do not love each other.
3. Nuture good thought, speak good words and do good actions.
4. Saying Assalamualikum is only one point Prophet (saw) is telling us in order to foster love amongst our self.