Hadith: By the One in Whose Hand my soul is! You will not enter Paradise until you believe and you will not believe until you love one another. Shall I tell you of something that, if you do it, you will love one another? Spread the greeting of peace among yourselves

عن أبي هريرة رضي الله عنه قال: قال رسول الله صلى الله عليه وسلم : «وَالَّذِي نَفْسِي بِيَدِهِ، لاَ تَدْخُلُوا الجَنَّة حَتَّى تُؤْمِنُوا، وَلاَ تُؤْمِنُوا حَتَّى تَحَابُوا، أَوَلاَ أَدُلُّكُم عَلَى شَيءٍ إِذَا فَعَلْتُمُوهُ تَحَابَبْتُم؟ أَفْشُوا السَّلاَم بَينَكُم».
[صحيح] - [رواه مسلم]

Abu Hurayrah (may Allah be pleased with him) reported: The Messenger of Allah (may Allah's peace and blessings be upon him) said: "By the One in Whose Hand my soul is! You will not enter Paradise until you believe and you will not believe until you love one another other. Shall I tell you of something that, if you do it, you will love one another? Spread the greeting of peace among yourselves."
Sahih/Authentic. - [Muslim]

Explanation

The chosen Prophet (may Allah's peace and blessings be upon him) started his speech with an oath to indicate the significance of his important advice. The advice contains ethical considerations, which, if followed, will lead to strong social cohesion. The Prophet (may Allah's peace and blessings be upon him) said: ''You will not enter Paradise until you believe.'' This is to be understood literally, as no one will enter Paradise until he believes. Even those who have a deficient belief will end up in Paradise, as explicitly stated in the Hadīth. Then the Prophet (may Allah's peace and blessings be upon him) said: ''You will not believe until you love each other.'' This means that your faith will not be perfect nor will your conditions be improved when you believe, unless you love one another. Finally, the Prophet's command to spread the greeting of peace encourages Muslims to spread the greeting of peace among the Muslims they know and those they do not know. The greeting of peace is a primary cause of harmony and love. By spreading it, Muslims enhance their unity and show the watchword that distinguishes them from people of other religions. In addition, spreading the greeting of peace leads to self-discipline, commitment to humbleness, and honoring the sanctity of Muslims.