´It was narrated from 'Abdullah bin 'Amr that:` A man asked the Messenger of Allah [SAW]: "What quality of Islam is best?" He said: "To feed (the poor) and to say the Salam to whomever one knows and whomever one does not know."
Hadith Referenceسنن نسائي / كتاب الإيمان وشرائعه / 5003
Hadith Gradingالألبانی:صحيح | زبیر علی زئی:متفق عليه