Spreading the greeting of peace (salam)

قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم: لاَ تَدْخُلُوا الْجَنَّةَ حَتَّى تُؤْمِنُوا, وَلاَ تُؤْمِنُوا حَتَّى تَحَابُّوا, أَوَلاَ أَدُلُّكُم عَلَى شَيْءٍ إِذَا فَعَلْتُمُوهُ تَحَابَبْتُم, أَفْشُوا السَّلاَمَ بَيْنَكُمْ

(The Messenger of Allah r said: ‘You shall not enter paradise until you believe, and you shall not believe until you love one another. Shall I not inform you of something, if you were to act upon it, you will indeed achieve mutual love for one another? Spread the greeting amongst yourselves.)

Source: Muslim 1/74.

ثَلاَثٌ مَنْ جَمَعَهُنَّ فَقَدْ جَمَعَ الْإِيمَانَ: الْإِنْصَافُ مِنْ نَفْسِكَ, وَبَذْلُ السَّلاَمِ لِلْعَالَمِ, وَالْإِنْفَاقُ مِنَ الإِقْتَارِ

(Aammar said: ‘Three characteristics, whoever combines them, has completed his faith: to be just, to spread greetings to all people and to spend (charitably) out of the little you have.)

Source: Al-Bukhari.

وَعَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ رَضِيَ اللَّهُ عَنْهُمَا: أنَّ رَجُلاً سَأَلَ النَّبِيَّ صلى الله عليه وسلم أيُّ الْإِسْلاَمِ خَيْرٌ قَالَ: تُطْعِمُ الطَّعَامَ, وَتَقْرأُ السَّلاَمَ عَلَى مَنْ عَرَفْتَ وَمَنْ لَمْ تَعْرِفْ

"(Aabdullah Ibn Aamr t reported that a man asked the Prophet r: ‘Which Islam is the best?’. He r replied: Feed (the poor), and greet those whom you know as well as those whom you do not.)

Source: Al-Bukhari, Muslim 1/65.