Credit Knife Person

There is a credit knife stall in the deepest corner of the flea market. The stall owner is an old man in his fifties. He doesn't sell knives, he only lends them on credit. Leave a prophecy and give away the knife for free. If the prophecy comes true, you will receive the money. Some say he is a liar, some say he is a lunatic. Until that day, a young man in a suit and leather shoes knelt in front of the stall, holding a knife in his hand - four words were engraved on the knife: Knife on credit, not on credit.