A man asked the Prophet, "What Islamic traits are the best?" The Prophet said, "Feed the people, and greet those whom you know and those whom you do not know."  

أَنَّ رَجُلاً سَأَلَ النَّبِيَّ ﷺ أَىُّ الإِسْلاَمِ خَيْرٌ قَالَ تُطْعِمُ الطَّعَامَ وَتَقْرَأُ السَّلاَمَ عَلَى مَنْ عَرَفْتَ وَعَلَى مَنْ لَمْ تَعْرِفْ  

The Prophet ﷺ said, "It is not lawful for a Muslim to desert (not to speak to) his brother Muslim for more than three days while meeting, one turns his face to one side and the other turns his face to the other side. Lo! The better of the two is the one who starts greeting the other."  

عَنِ النَّبِيِّ ﷺ قَالَ لاَ يَحِلُّ لِمُسْلِمٍ أَنْ يَهْجُرَ أَخَاهُ فَوْقَ ثَلاَثٍ يَلْتَقِيَانِ فَيَصُدُّ هَذَا وَيَصُدُّ هَذَا وَخَيْرُهُمَا الَّذِي يَبْدَأُ بِالسَّلاَمِ وَذَكَرَ سُفْيَانُ أَنَّهُ سَمِعَهُ مِنْهُ ثَلاَثَ مَرَّاتٍ