أَنَّ رَجُلاً، سَأَلَ رَسُولَ اللَّهِ صلى الله عليه وسلم أَىُّ الإِسْلاَمِ خَيْرٌ قَالَ " تُطْعِمُ الطَّعَامَ، وَتَقْرَأُ السَّلاَمَ عَلَى مَنْ عَرَفْتَ وَمَنْ لَمْ تَعْرِفْ ".
Abdullah ibn Amr reported: A man asked the Messenger of Allah ﷺ, “What in Islam is best?” He said, “That you feed (others) and give the greeting of peace to those you know and those you do not know.”
also in Sahih al-Bukhari 12