Bava Metzia 5:1 - 5:2

איזהו נשך שהוא נושך – that he took from him what he (i.e., the other) didn’t give him.

המרבה בפירות – he increases the reward for himself with produce, and whether by the loan of money or whether by the loan of produce it is interest, for he increases his money. But the concluding part of the Mishnah deals with Rabbinic interest, as it explains – which through the means of commercial transactions.

דינר זהב – twenty-five silver denars.

וכן השער – Such is how they were sold in the city, and it was permissible for him to give money now on the condition that he would give him the wheat all the days of the year with these monies according to the monetary rate, and even though that he doesn’t have the wheat right now. It is taught [in the Mishnah] of our chapter (Mishnah 7):, “when the market price is out, you may purchase, for although he (i.e., the seller) has not goods as yet, others have,” and this seller can purchase them now with these monies.

עמדו חטין בשלשים דינרים אמר לו תן לי חיטי – and this is permissible, if he gives him the wheat, but if he fixed a price to give him for them wine, it is prohibited, lest the wine become more expensive, for since he doesn’t have any wine. And even though he fixed a price with him according to the current market price of wine, and the market price had gone out. For since he doesn’t give him money that we would be able to say that he could purchase wine with these monies tha the received, but he makes the value of the wheat an obligation and to set a price on his obligation of wine, this is prohibited if he lacks wine. For if he had wine, it would be purchased to him from now to the person who comes to set a price on the obligation of wine, and when it went up in price, it was in his possession when it went up in price.

מרבים על השכר – the wages in money for waiting for the rental.

ואין מרבין על המכר – the wages in waiting for the sale. And the reason is that the rental is not completely paid off until the end; therefore, when he takes from a Sela per month which is twelve Selas [per year], this is not the wages in waiting for the monies, for he was not obligated to pay him the rent until the end of the month, and that which he said to him: “if you give it to me now, it is yours for ten Selas, if he would give it to him early, he would forgive him the cost of the rental and diminish it for him for less than its value. But regarding a sale, then you make use of the object and the law is to give the money, and when he (i.e., the seller) says to him (i.e., the buyer): “if from now you give me, it is yours for one-thousand zuz, which is its cost and if it has already been at the granary, it is the reward for waiting for the monies [and is forbidden, as interest].

מכר לו את השדה – And the same law applies for movables, and all business, if he sold it to him for more than its worth with the wages for waiting for the monies, it is forbidden, for it is the dust of interest according to the Rabbis And all dust of interest (i.e., indirect interest), if he gave it, it is not reclaimed through judges, whereas stipulated/direct usury from the Torah, is reclaimed through judges [i.,e in court] (see Talmud Bava Metzia 61b).