Bava Metzia 74B

ימות הגשמים ⁠– איכא בינייהו.

The practical difference between them is with regard to the winter. According to the first tanna one may set a price for the future delivery of manure at any point in the year, including the winter, but according to the Rabbis one may not arrange for the delivery during the winter, because manure is not commonly available then.

ופוסק עמו כשער הגבוה.

§ The Mishnah teaches: One may set a price at the highest rate, meaning he may set a price for the future delivery of produce and stipulate that if the market rate falls below the agreed-upon price, he will purchase the product according to the lowest price in effect in the market at any point during the year, which is the price that will provide the highest amount of merchandise for the amount he agreed to pay.

ההוא גברא דיהיב זוזי לנדוניא דבי חמוה, לסוף זל נדוניא. אתו לקמיה דרב פפא. אמר ליה: אי פסקת (עמו) כשער הגבוה ⁠– שקל כהשתא. ואי לא ⁠– שקל כי מעיקרא.

The Talmud relates: There was a certain man who gave money to sellers to buy jewelry for his betrothed’s dowry [linduneya] on behalf of his father-in-law, as his intended father-in-law made him an agent to buy the jewelry for part of the dowry. The betrothed man stipulated with the sellers that they would provide the jewelry in time for the wedding. Ultimately, the jewelry for the dowry became less expensive, as the price fell. The betrothed man wanted to retract his commitment to buy the jewelry at the higher price. The parties came before Rav Pappa for a ruling. Rav Pappa said to the betrothed man: If you set a price with the seller to buy the jewelry at the highest rate, i.e., the largest amount of jewelry for the price you are willing to pay, then take the jewelry at the present price. But if not, take it at the price that you set initially.