Nosson and Shimon were roommates. One evening, they were sitting in their room studying when Shimon noticed leftover hamentashen from Purim sitting on the table. “What are you going to do with those hamentashen?” Shimon asked.
“I don’t need them anymore. They’re hefker,” Nosson replied.
“Glad to hear,” Shimon said. “Often, late at night, I get hungry. I can put them to good use!”
Later in the evening, Shimon overheard Nosson talking to his brother outside. “I still have hamentashen in my room,” Nosson said. “If you want, you can take them.”
Shimon’s ears perked up. “I was planning on eating them tonight,” he said to Nosson. “You declared them hefker!”
“But you didn’t take them yet,” replied Nosson. “They’re still sitting on the table in the room.”
“Well, then I’m going to take them right now!” announced Shimon. He began walking briskly to the room. Nosson starting walking after him. Shimon began running.
“I take back my hefker declaration,” Nosson shouted. “I still want my hamentashen. You may not take them!”
“Too late,” said Shimon. “They’re already hefker and I’m going to eat them now!”
Nosson began running after him. Shimon ran past the beis midrash and nearly bumped into Rabbi Dayan, who was just walking out.
“I’m sorry,” apologized Shimon.
“What’s the big rush?” Rabbi Dayan asked.
“We have a question,” Nosson said and explained the situation to Rabbi Dayan.
“Once a person makes something hefker, he cannot take back his declaration,” replied Rabbi Dayan. “He can, however, seize the item first and reacquire it. In your case, though, it’s questionable whether the hefker declaration was valid.” [Choshen Mishpat 273:2,4; see Ketzos 273:1]
“Why?” asked Shimon.
“The Gemara [Nedarim 45a] teaches that a hefker declaration must be made before three people,” explained Rabbi Dayan. “Although the Torah validates a hefker declaration before one person, the Sages required three people so that one person can acquire the item and the other two can serve as witnesses. This rule was made partly to thwart fictitious hefker declarations of land to evade tithing requirements.” [Choshen Mishpat 273:7]
“The Rema, however, writes that some maintain that even hefker declarations made in private, when alone, are valid,” continued Rabbi Dayan. “The Sma [273:11] argues that the Rema only disputes the first point – that Torah law does not require even one person. He agrees, though, that the Sages require three.
“The Gra [273:8], however, explains that the Rema disputes both points and that the Rema maintains that the Sages required three people only to establish a tithing exemption. As for the question of ownership, no people need be present.”
“So, according the Sma, the hefker was not valid,” noted Nosson.
“Seemingly. Even so, Tosafos and the Rosh in Nedarim suggest that hefker declarations of movable items requires only one person present, even according to the Sages,” said Rabbi Dayan.
“The one who took the item believed that the initial owner made the item hefker since he could claim alternatively – migo – that he purchased the item. Other authorities do not distinguish between real estate and movable items.” [Chochmas Shlomo 273:7; Machaneh Ephraim, Hil. Zechiya Mei’hefker #1; Aruch Hashulchan 273:7; Pischei Choshen, Kinyanim 23:5]
“Thus, due to the dispute about hefker declarations before one person, the rule of hamotzi meichaveiro alav hare’ayah (the burden of proof is on the claimant) applies,” concluded Rabbi Dayan, “Shimon should not take the hamentashen against Nosson’s will, but if he already took them, he can keep them.” [Sma 273:12; Mishneh Halachos 9:325]