A man asked the Messenger of Allah (May peace be upon him): When aspect of Islam is best? He replied: that you should provide food and greet both those you know and those you do not know.
أَنَّ رَجُلاً سَأَلَ رَسُولَ اللَّهِ ﷺ أَىُّ الإِسْلاَمِ خَيْرٌ قَالَ تُطْعِمُ الطَّعَامَ وَتَقْرَأُ السَّلاَمَ عَلَى مَنْ عَرَفْتَ وَمَنْ لَمْ تَعْرِفْ