Musannaf Ibn Abi Shayba 19:11

Abu Bakr narrated to us, he said: Sharik narrated to us, from Sa'id ibn Masruq, from Ikrimah, who said: A bag belonging to Ammar was stolen at Muzdalifah. He placed his pouch in its tracks and called the trackers. They said: "An Abyssinian." They followed his tracks until he reached a wall while he was turning it over. He [Ammar] took it and left him. It was said to him [regarding why he let the thief go], and he said: "I will cover for him, perhaps Allah will cover for me."