Bava Metzia

if the vendor retains the title thereto, it is permitted; if the vendee, it is forbidden.  If he was transporting provisions from place to place, when his neighbour met him and proposed, 'Let me have them, and I will supply you [later] with provisions that I have there,' if he actually possesses provisions there, it is permitted;  if not, it is forbidden. But carriers  supply in the dearer place at the prices of the cheaper,  without fear [of incurring the guilt of usury]. Why? — R. Papa said: They are satisfied by being informed of the market price.  R. Aha the son of R. Ika said: They are satisfied with the extra discount they receive.  Wherein do they differ? — In respect of a new trader. In Sura four [se'ahs] went [to the zuz]; in Kafri,  six. So Rab gave money to the carrier,  accepted himself the risks of carriage, and received five [se'ahs per zuz]. But why not take six?  — For a man of great repute it is different. R. Assi propounded of R. Johanan: May this be done with small ware?  — He replied: R. Ishmael son of R. Jose wished to do so with linen garments, but was not allowed by Rabbi. Others say, Rabbi wished to do so with small ware, but R. Ishmael son of R. Jose did not allow him. An orchard:  Rab forbade it; Samuel permitted it. Rab forbade it: Since it is worth more later on, it looks like payment for waiting.  Samuel permitted it: Since there may be cause for regret,  it does not look like payment for waiting.  R. Shimi b. Hiyya said: But Rab agrees [where the ploughing is done] with [the aid of] oxen, since great loss is caused. Samuel said to those who advance seed grain to be returned in new grain:  Busy yourselves  in the field, that ye may have a title to the soil itself;  for if not, it will be accounted as a loan to you, and forbidden. Raba advised those who keep watch over the cornfields: Go out and find some occupation  in the barn, that your wages may not be payable until then;  since wages are not payable until the end [of one's task], and it is only then that they make you the gift. The Rabbis protested to Raba: You enjoy usury. For everyone [who leases a farm] accepts four [kor as annual rent] and dismisses the tenant in Nisan;  whilst you wait until Iyar  and receive six.  He retorted: It is you who act contrary to the law; the land is in bond to the tenant;  if you make him quit in Nisan [before the crops are ripened], you cause him much loss. Whereas I wait until Iyar, thus greatly enhancing his profits.