It is narrated from Sayyiduna Ali (may Allah be pleased with him) that Sayyiduna Mughirah bin Shu'bah (may Allah be pleased with him) had a spear. Whenever we went on an expedition with the Messenger of Allah (peace and blessings be upon him), Sayyiduna Mughirah (may Allah be pleased with him) would take it with him and plant it in the ground and deliberately leave it behind. People would pass by it and pick it up. I said: If I come to the Noble Prophet (peace and blessings be upon him), I will definitely inform him about this action. When the Prophet (peace and blessings be upon him) came to know of this, he said: If you start doing this deliberately, then lost property will not be picked up.