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

a man asked the Messenger of Allāh ﷺ which command of Islam is best. He said: You should feed others, and give the greeting of salam to everyone, whether you know them or not.