Bava Metzia

We reason, 'What is the difference between them themselves [sc. the crops] and their value?' we argue [conversely] too, 'What is the difference between their value and them themselves?' and [consequently] one may contract to supply [provisions] at the current market price even if he has none.  R. papa and R. Huna the son of R. Joshua objected to Raba's [statement]: In all these cases, if he possesses [these commodities], it is permitted; if not, it is forbidden!  — He answered them: There [the reference is to] a loan, here to a sale. Rabbah and R. Joseph both said: Why did the Rabbis rule, A man may contract to supply [provisions] at the current market price, even if he has none? Because he [the purchaser] can say to him [the vendor], 'Take your favours and throw them in the bush! How do you benefit me? Had I money, I could have bought cheaply in Hini and Shili.'  Abaye said to R. Joseph: If so, should it not be permitted to lend a se'ah for a se'ah, since he [the borrower] could say, Take your favours and throw them in the bush! For,' he could argue, 'would my wheat have gone to ruin in my granary?' — He replied: There it is a loan, here a purchase. R. Adda b. Abba said to Raba: But he would have to pay money to a broker!  — He replied: He [the purchaser] must give that too to him. R. Ashi said: people's money is their broker. Rabbah and R. Joseph both said: He who advances money at the early market price  must [personally] appear at the granary. For what purpose? If to acquire it — but he does not thereby acquire it!  If that he [the vendor] may have to submit to [the curse], 'He who punished, etc.,'  — even without his appearing there, he must submit thereto! — In truth, it is that he may submit to the curse; but he who advances money on an early market generally gives it to two or three people:  hence, if he appears before him, [he shews] that he relies upon him [for supplies]; but if not, he [the vendor] can plead, 'I thought that you found better produce than mine, and bought it [intending that I should return your money].' R. Ashi said: Now that you say it is because of his relying upon him, then even if he met him in the market and said to him, ['I rely upon you',] he relies upon him. R. Nahman said: The general principle of usury is: All payment for waiting [for one's money] is forbidden. R. Nahman also said: If one gives money to a wax merchant, when it is priced at four [standard measures per zuz], and he [the vendor] proposes,'I will supply you five [per zuz];'  if he possesses it, it is permitted; if not, it is forbidden. But this is obvious!  — It is necessary [to teach this] only when he has [wax] credits in town:  I might think that in such a case it is as though [he had said, 'Lend me] until my son comes, or until I find the key:'  therefore he teaches, since it must yet be collected, it is as non-existent. R. Nahman also said: If one borrows money from his neighbour and found a surplus therein, if it is an amount about which there could be an error, he must return it; otherwise, it is simply a gift. When is it 'an amount about which there could be an error'? — R. Abba, the son of R. Joseph said: