Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) narrates: A man from Banu Sulaym passed by some companions of the Prophet (peace and blessings be upon him), and that man had some goats with him. The man greeted them with salam, but those people said: "He only greeted you so that he could be safe from you." They attacked him, killed him, and took his goats. Then they brought those goats to the Prophet (peace and blessings be upon him), so Allah the Exalted revealed this verse: "O you who believe! When you go forth in the way of Allah, investigate carefully..." — and the verse continues to the end.