Hazrat Abu Balaj (may Allah have mercy on him) narrates that I heard Hazrat Mus'ab bin Sa'd (may Allah have mercy on him) say that Hazrat Sa'd (may Allah be pleased with him) made a contract of emancipation (mukataba) with one of his slaves. He asked the slave for some money, but the slave replied, "I have nothing to give you." However, Hazrat Sa'd (may Allah be pleased with him) had demanded some dinars which the slave had hidden in his shoes. So Hazrat Sa'd (may Allah be pleased with him) invoked a curse against him, and both of his shoes were stolen.