Musannaf Ibn Abi Shayba 28:577

'Abd al-Rahim ibn Sulayman narrated to us, from Isra'il, from Simak, from 'Ikrimah, from Ibn 'Abbas, who said: A man from Banu Sulaym (Hashim) passed by a group of the Companions of the Messenger of Allah, peace and blessings of Allah be upon him, while he had sheep with him. He greeted them with peace, but they said, "He only greeted you to seek protection from you." So they went to him and killed him and took his sheep, then they brought them to the Messenger of Allah, peace and blessings of Allah be upon him. Then Allah the Exalted revealed: "O you who have believed, when you go forth in the cause of Allah, investigate; and do not say to one who gives you [a greeting of] peace, 'You are not a believer,' aspiring for the goods of worldly life; for with Allah are many spoils," until the end of the verse.