A man cannot convey a thing that has not come into the world, whether by sale, or by gift, or by the gift of one on his deathbed. How so? "What this field shall produce is sold to you"; "What this tree shall bring forth is given to you"; "Give what this animal shall bear to so-and-so" — he has acquired nothing. And so in all cases like this.
One who sells the fruit of a palm to his fellow may retract even after the fruit has come into the world; and if the buyer snatched it and ate it, it is not taken out of his hand. And whichever of the two retracts is not bound to receive the mi she-para, the curse the court pronounces upon one who goes back on his word.
But one who contracts at the rate current in the market, when the kind of produce upon which he contracted was not in the seller's possession, is bound to buy it and to give the buyer what he contracted for; and if he retracts, he receives the mi she-para.
One who contracted at the rate current in the market to give four se'ah for a sela: if it was still in the ear, the transaction has taken effect so far as to receive the mi she-para. And this is when he presented himself to him at the threshing-floor, or said to him in the market, "I am relying upon you." But if he did not appear to him at the threshing-floor and did not say to him, "I am relying upon you," the seller's mind did not rest upon the matter, and he does not receive the mi she-para — for he says, perhaps he has contracted with another and has no need of this wheat.
A thing that is not in the possession of the one conveying it is not acquired, and it is as a thing that has not come into the world. How so? "What I shall inherit from my father is sold to you"; "What my net shall bring up from the sea is given to you"; "This field, when I acquire it, is acquired to you" — he has acquired nothing. And so in all cases like this.