(Imam Bukhari narrates that) Amr bin Khalid said: Laith narrated to us, from Yazid, from Abi Al-Khair, from Abdullah bin Amr (may Allāh be pleased with both of them), he says that

a man asked the Prophet ﷺ which trait of Islam is best. He said: You should feed others and give the greeting of salam, both to those you know and those you do not know.