Musannaf Ibn Abi Shayba 19:868

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Sufyan narrated to us, from Habib ibn Abi ‘Amrah, from Sa’id ibn Jubayr, who said: Al-Miqdad ibn al-Aswad went out in a military expedition, and they passed by a man with some sheep of his. They wanted to kill him, so he said: "There is no god but Allah." Al-Miqdad said: "I wish his family and his wealth were near." He said: When they arrived, they mentioned that to the Prophet, peace and blessings of Allah be upon him, and it was 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." He said: The booty. "For with Allah are many bounties. Thus – you were before." He said: You were concealing your faith from the polytheists. "Then Allah conferred His favor upon you." He said: So Islam was made manifest. "Investigate." He said: A warning from Allah. "Indeed Allah is ever, with what you do, Acquainted."