If a person is bringing merchandise from place to palace and his friend requests that he give him the merchandise and he will pay him the price he could have received in that place if the seller is responsible for the merchandise it is permitted. (1)
If the buyer is responsible for the merchandise it is forbidden because it is considered that he is borrowing the money right now and consequently he is repaying more than he received.
If a person is bringing produce from place to palace and his friend requests that he give him the produce and he will repay him with produce that he owns elsewhere if he owns the produce it is permitted but if not it is forbidden. (2)
Merchants who bring grain from place to place may take money from customers in a place where the grain is more expensive on condition that they will supply them the produce at the less expensive price and it is not Ribis. (3)
If he only recently became a merchant it is a Machlokes Amora'im if he may take money from customers in a place where the grain is more expensive on condition that he will supply them the produce at the price of a less expensive place. (4)
It is forbidden to take money from customers in a place where linen or pieces of metal are more expensive on condition that he will supply it to them at the price of a less expensive place. (5)
Rav holds it is forbidden to pay in advance for wine if the grapes have not yet ripened because he is getting a cheaper price because he is advancing the money, while Shmuel holds it is permitted. (6)
Rav admits to Shmuel that in a place where the grapes are harvested with oxen that it is permitted to pay in advance for the wine because it is more likely that the vines will be ruined and will not produce grapes.
If someone lends grain for planting on condition that he will be repaid the grain from the new crop he must help out a little with the plowing and harvesting and otherwise it is Ribis and it is forbidden. (7)
If someone is hired to guard grain until it is harvested if he is not paid until after the grain is piled up and smoother over he must help out a little with the threshing of the grain and otherwise it is Ribis. (8)
A Stam Mashkon is for a year and the borrower may not take back the Mashkon within a year even if he repays the loan.
It is permitted to pay money for wine in Tishrei on condition to receive good wine in Teves even though the seller is responsible if the wine turns into vinegar. (9)
It is permitted to take a Jewish person who is not acting properly and work him like a servant.
A BIT MORE
1. The seller is bringing it to a place where he can receive a higher price for the merchandise and even though the buyer is repaying at the higher price it is permitted because it is not a loan until he sells it and thus he is repaying the exact amount that he is borrowing.
2. Because it is regarded as if the produce that he owns elsewhere is right now in the possession of the lender even though he did not do Meshichah. Since the Isur to lend one Se'ah of produce for another Se'ah is only Avak Ribis d'Rabanan in a case that the borrower has the produce in his possession the Rabanan do not prohibit it.
2. R. Papa says the reason why it is not Ribis is because by virtue of receiving money from the customers in advance they get a good name and people recognize them as merchants and even if they were not given the money in advance and they must immediately come back with the merchandise they would be willing to make the deal. R. Acha Bar Ika says that the reason that it is permitted is because he is hoping that his supplier in the inexpensive place will give him a better price when he finds out that he is not making a profit on it.
4. According to R. Papa it is permitted because he is doing it because he wants to be recognized as a merchant, while according to R. Acha Bar Ika it is forbidden because since he is a new merchant his supplier will not believe him that he is not making a profit and he will not be willing to give to him at a cheaper price..
5. Because the reasons that he wants to be recognized as a merchant or that his supplier will be willing to give it to him at a cheaper price only apply to grain which is commonly available, but it doesn't apply to metal or linen garments because they are not commonly available and a merchant doesn't buy from the same supplier each time and he doesn't buy the same merchandise each time.
6. Shmuel holds it is permitted since the buyer is taking responsibility that if the vines get ruined and don't produce grapes that he will take the loss.
7. If he doesn't help out it is forbidden because it is Avak Ribis to lend a Se'ah on condition to be repaid a Se'ah as maybe the price of the Se'ah will go up in the meantime, but of he helps in the plowing and harvesting he is making a Kinyan on the land and it is as if he is buying the land and it is permitted.
8. If he doesn't help out it is Ribis because they are delaying with the payment of his wages until after the grain is place in piles and in return they are paying him extra therefore he should help thresh the grain and since he is a hired hand he payment is not due until the work is completed and even if they pay him extra it is not Ribis since he is receiving his payment exactly when it is due and it is not payment friend delaying his wages.
9. Even though the seller is taking responsibility for the wine it is not considered a payment for advancing the money because if the wine turns into vinegar it was already starting to go bad in Tishrei and the buyer gave money for wine not for vinegar.
If a person is bringing merchandise from place to palace and his friend requests that he give him the merchandise and he will pay him the price he would have received in that place if the seller is responsible for the merchandise it is permitted. The Rosh says it is only permitted if the seller gives him wages for his effort and the Chidush is that I may think it is forbidden even though he is giving him wages because of the concern that he will be negligent with his wages. The Pilpula Charifta explains that he may be negligent with paying him the wages because maybe he will say that I was planning to make the effort to travel to the expensive place and I didn't need you to travel for me and therefore I don't have to pay you.
It is forbidden to buy fruit of the orchard before they are ripe because the seller is selling fruit that is worth 20 when it is ripe for only ten and therefore that which he is undercharging is a reward for advancing the money. But it is permitted to buy a calf for a cheap price and to allow the seller to hold on to it until it grows because if it dies or becomes weak it is in the possession of the buyer and death is common. (Shulchan Aruch YD 173:10)