62:14 If one person gives another person money in order to acquire real estate or goods for him, if the agent goes and buys the object for himself, if he used his own money, he is considered deceitful. If he used the money he was given by the one who sent him, he is obligated to turn the object over to him even though the agent’s intention was to acquire it for himself.
62:15 If a person has made even a small deposit as a down payment on a purchase, or if he has marked the item as his in the seller’s presence or at the seller’s direction, even though the sale is not yet complete, it is inappropriate for either party to then cancel the transaction. Doing so is considered conduct unbecoming a Jew and the one who reneged is formally censured by the courts. They recite a text to the effect that G-d, Who punished the generation of the flood, the generation of the Tower of Babel, Sodom and Gemorah, and the Egyptians, will likewise punish those who fail to keep their word.