Hazrat Ikrimah narrates that Hazrat Ibn Abbas (may Allah be pleased with them both) said: A man from the tribe of Banu Sulaim passed by the companions of the Messenger of Allah (peace and blessings be upon him) while he had sheep and goats with him, so he greeted them with salam. They said: He has not greeted you except to protect himself from you, so they intended (harm) towards him and killed him and took his sheep and goats. And they brought them to the Messenger of Allah (peace and blessings be upon him). Upon this, Allah the Lord of Honor revealed this verse: "O you who believe! When you go forth (for jihad) in the way of Allah, investigate thoroughly, and do not say to the one who greets you with peace, 'You are not a believer,' seeking the goods of worldly life; for with Allah are abundant spoils." (__QUR_N__, etc.)