once
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)).
Meaning
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.
Source and references
Hisn al-Muslim, entry 226.The reference is copied from the edition; separate editorial verification is not complete yet.
Source edition: Fortress of the Muslim. Open source ↗