Siman 189

A transaction is not finalized by words, for if one says to his fellow, "How much will you give me this object for?" and he said to him, "For such and such," and both agreed and set the price, each of them may retract, even if this was before witnesses, and even if they said to the witnesses, "Be witnesses for us that Reuven sold and Shimon bought," this is nothing until the transaction is finalized by way of a kinyan for each and every thing as is appropriate for it: land according to its kinyan and movables according to their kinyan. After the kinyan, neither of them can retract even if there were no witnesses to the matter, for in monetary laws, witnesses were only created for liars, as has been written in siman 241. And if the kinyan for land was by way of a shetar, one cannot cancel the sale even when the buyer returned the shetar to the seller, for this is nothing [Bach]. And even if they forgave one another afterward, it is of no effect, whether he said, "I hereby forgive you the kinyan," or whether he said, "I hereby forgive you the transaction," for the language of mechilah only applies to a debt and not to land and not to objects, but rather to money that is in the hand of the one being forgiven, as has been written there. And a person does not withdraw from what is in his hand except through one of the methods of acquisition, such as with movables where the seller would return and perform meshikhah or hagbahah on them, and with land where the seller would perform hazakah on the land, or the buyer would write him a shetar of sale, or a kinyan of money, or a kinyan of chalifin. However, if he swore or gave a handshake or accepted by a formal obligation to sell this object or this land to so-and-so, even though he is obligated to fulfill it because of the oath as has been written in siman 209, nevertheless, since this is not a kinyan, if that so-and-so forgave him the oath, it is a mechilah and he is exempt from his oath. And he must say, "Behold, I am as if I have received," in the manner that was explained in Yoreh Deah siman 232 [it appears to me].

In all kinyanim, the buyer must intend to acquire and the seller to transfer ownership, but if he performed meshikhah or hagbahah or performed hazakah and did not intend to acquire, he has not acquired. See in siman 260, section 2, that without intent for kinyan it is merely the act of a monkey, and by what means would the object or the land change from domain to domain? And so too, if Reuven has a deposit in the hand of Shimon, and Reuven revealed his mind that his desire is to sell it for such and such an amount, only that he did not find a buyer, and now Shimon agreed to retain it as a purchase, he cannot acquire it without the knowledge of Reuven, even though it is known to us that Reuven's desire is to sell it for this price, since he did not transfer it to him now. And if Reuven says, "I transfer it to you for such and such," the object is immediately acquired by Shimon, for his domain acquires for him. This is not like the one who disagrees in this and holds that even in such a case he has not acquired, because since he gave him permission to deposit with him, the place of the object is in the domain of the depositor; for since he transfers the object to him, automatically its place is also acquired by him since it is his, and his hatzer and his acquisition come as one. And the same law applies if he gave it to him as a gift, he acquires in such a case, for his hatzer and his gift come as one. And so too regarding kiddushin when he says to a woman, "Be betrothed to me with the deposit that I have in your hand," as is written in Even HaEzer siman 28. And if the deposit is in the hand of another, he has not acquired even when the seller says to him that he should acquire, until he rents the place or pulls it into his domain or lifts it, as is written in siman 200; and he can appoint an agent who shall acquire on his behalf, as is written there.

And even though words do not constitute a kinyan, nevertheless it is proper for a person to stand by his word, and anyone who retracts his words is considered lacking in faithfulness and the spirit of the sages is not pleased with him. And some say that even if the price has changed, he is called lacking in faithfulness, and it will be explained in siman 204 with the help of Heaven.