Mr. Zahtz purchased seats for Rosh Hashanah in his regular shul. Exactly one week before Rosh Hashanah, though, his son Zevi had a boy.

“That means a Rosh Hashanah bris,” Mr. Zahtz realized.

“Where will the bris be?” Mr. Zahtz asked his son a few days later.

“We’ll be staying with my in-laws for Rosh Hashanah, so the bris will be there,” said Zevi. “We hope you’ll be able to come.”

“Of course!” replied Mr. Zahtz. “We’ll come if they can arrange a place for us to stay.”

“They already have a place next door,” Zevi said. “Seats are also still available in their shul, but will cost $100.”

“We already paid $100 for seats, but we’ll pay again,” said Mr. Zahtz. “It’s worth it for the occasion!”

On Rosh Hashanah, Mr. Zahtz’s regular seat was empty. His neighbor, Mr. Spier, had a son visiting.

“This seat will be empty all Yom Tov,” Mr. Spier said to his son. “Mr. Zahtz is away for his grandson’s bris, so you can sit there.”

When Mr. Zahtz returned, Mr. Spier greeted him.

“Mazel tov on your grandson’s bris,” he said. “I also want to thank you for use of your seat on Rosh Hashanah.”

“What do you mean?” asked Mr. Zahtz.

“Our son was with us for Rosh Hashanah,” Mr. Spier explained. “Since I knew you were away, I told him he could sit in your seat for all of Yom Tov.”

“I normally wouldn’t make a fuss,” Mr. Zahtz said, “but I paid $100 for that seat and had to pay another $100 for seats at my son’s in-laws’ shul. If you used my seat, you should reimburse me.”

“But you weren’t using it anyway,” argued Mr. Spier. “It would have remained vacant!”

“You still had no right to use it without my permission,” said Mr. Zahtz emphatically. “Just as I paid for seats where I visited, you owe me $100 for my seat that your son used!”

Just then, Rabbi Tzedek walked by and overheard the two arguing.

“What’s going on?” he asked politely. “We don’t want unnecessary disputes during the days before Yom Kippur!”

Mr. Zahtz told Rabbi Tzedek what had happened. “Does Mr. Spier have to reimburse me $100 for my seat?” he asked.

“This case relates to a concept called ‘zeh neheneh v’zeh lo chaser’ (this one gained; that one did not lose),” replied Rabbi Tzedek. “If someone squats on another’s property that is not for rent, without causing any loss, he is not obligated to pay afterward for the benefit (C.M. 363:6). In this case, Mr. Zahtz had no intention of renting his seat, and Mr. Spier’s benefit did not cause him any loss, so he does not have to pay.”

“But I did lose, because I paid for the seat!” exclaimed Mr. Zahtz.

“So does anyone else who acquires a property,” answered Rabbi Tzedek. “We are not discussing the initial outlay for the property, but whether the benefit of the second party caused an additional loss, which it did not.”

“What if I simply don’t want anyone sitting in my seat?” asked Mr. Zahtz. “If I’m not there - let it remain empty!”

“There is also a concept called ‘kofin al middas Sedom,’” replied Rabbi Tzedek. “In Sedom, people refused to let others benefit from their property even when it did not entail any loss to them; this behavior is frowned upon.

“Sometimes, we even force people not to act this way,” continued Rabbi Tzedek. “However, this applies only when the owner cannot gain from his property, yet wants to withhold benefit from others. Where he can gain, though - e.g. by renting - and does not want to, we cannot force him to allow others to use it (Rama 154:3; 363:6; Pischei Choshen, Geneivah 8:1-3).”

“Had Mr. Zahtz said, ‘No,’ and my son sat there anyway, would I still be exempt?” asked Mr. Spier.

“If Mr. Zahtz explicitly said not to sit there,” answered Rabbi Tzedek, “you would have to pay for the use (363:6).

“I would add, though,” concluded Rabbi Tzedek, “that, especially on Rosh Hashanah, it is a privilege and merit to have someone use your vacant seat for davening (prayer).”