Hazrat Ata Madani says that a man sold some goods, then the buyer claimed there was a defect, and they brought this dispute to Hazrat Uthman bin Affan (may Allah be pleased with him). The buyer said, "Swear by Allah that when you sold it to me, there was no defect in it." The seller said, "I swear that when I sold this thing to you, I had no knowledge of any defect in it." Hazrat Uthman (may Allah be pleased with him) said, "This man has done justice to you."