Mr. Fine had granted a $20,000 interest-free loan to Mr. Schnur for the period of a year. At the end of the year, he turned to Mr. Schnur to collect the loan.

“It’s a little difficult for me to repay now,” said Mr. Schnur. “Could you give me another month?”

“A month is OK,” said Mr. Fine, “but after that I’ll need the money without further delay.”

A month later, Mr. Fine asked to Mr. Schnur to repay the loan. Again Mr. Schnur weaseled out of payment. “I’m getting the money together,” he said. “Come back next week.”

“I can’t wait the week,” said Mr. Fine. “There’s a stock I’ve been watching carefully, STARS Inc., which I expect to begin climbing in the coming days. If you don’t repay immediately, I will have to take a loan from my broker to purchase the stock.”

“I’d pay you if I could,” said Mr. Schnur, “but I don’t have the money available.”

Mr. Fine turned away empty-handed. As he left, he said: “If STARS goes up, I’m going to hold you liable for the potential gain that I lost and/or the interest I will have to pay my broker for the loan.”

Sure enough, by the end of that week, STARS rose 6 percent. Mr. Fine again asked Mr. Schnur for the loan, but the request was again rejected. Mr. Fine took out a loan from his investment broker to purchase the stock, at a 3-percent rate of interest.

Mr. Schnur finally repaid the loan six months later. Mr. Fine demanded that he also pay the 6-percent gain he had missed out on, plus the interest he paid to his investment broker.

“I’m willing to compensate you for the interest that you paid,” agreed Mr. Schnur, “but not the 6 percent.”

“What’s the difference?” argued Mr. Fine. “You caused me a loss in both ways!”

The two came to Rabbi Dayan.

“A borrower is not allowed to delay payment against the lender’s will, if he is able to pay,” replied Rabbi Dayan (C.M. 97:3; Pischei Choshen, Halvaah 2:7).

“Nonetheless, if the borrower delayed payment, he is not liable for the lender’s loss of potential gain,” continued Rabbi Dayan. “The Yerushalmi (B.M. 5:3) writes that mevatel kiso shel chaveiro — a person who restrained his friend’s money and prevented him from earning profit — has only a complaint against him. Many authorities consider mevatel kiso shel chaveiro a form of grama, though, so that a chiyuv b’dinei Shamayim remains (Shach C.M. 292:15; Pischei Choshen, Nezikin 3:29; see, however, Shach 61:10; Responsa Imrei Binah #1).

“But I warned Mr. Schnur that I would hold him responsible,” Mr. Fine said.

“The Rashba (Responsa 3:227) rules that even if the lender stipulated that the borrower would be responsible for any loss or expenditure due to delayed payment, loss of potential gain is not considered a loss, based on the aforementioned Yerushalmi and other sources,” replied Rabbi Dayan. “Furthermore, he writes that in the case of a loan we cannot allow the borrower to pay the potential gain, since it would be ribbis (interest), as the lender always has potential gain with his money.

“In addition, if the lender chose to take an interest-bearing loan from a non-Jew, that is not considered a direct loss, and the borrower cannot cover the interest payment,” concluded Rabbi Dayan.

“However, some allow compensating the lender if the delay caused him a loss of capital, not just potential profit. Furthermore, some suggest that it is permissible to give compensation as a gift after repaying, without mentioning that it is due to the loan” (Taz, Y.D. 170:3; Pischei Choshen, Halvaah 2:10; Bris Yehudah 2:14-15[35]).