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 reported that a man asked the Prophet : ‘Which Islam is the best?’. He replied: Feed (the poor), and greet those whom you know as well as those whom you do not.)
Al-Bukhari, cf. Al-Asqalani, Fathul-Bari 1/55, Muslim 1/65.