If one said: This field will be ownerless for one day, for one week, for one month, for one year, or for one seven-year Sabbatical cycle, as long as no one took possession of the field, neither the one who declared it ownerless nor another person, he is able to retract his declaration. Once one took possession of the field, whether it is he or whether it is another person, he is unable to retract his declaration. This baraita is difficult, as the first clause is apparently in accordance with the opinion of the Rabbis, who hold that rendering property ownerless is unilateral and not contingent upon whether one took possession of it, and the latter clause is in accordance with the opinion of Rabbi Yosei, who holds that rendering property ownerless is complete only when one takes possession of that property.

Ulla said: The latter clause is also in accordance with the opinion of the Rabbis. The Gemara asks: If so, why is the ruling in the baraita: As long as one did not take possession of the field, neither the one who declared it ownerless nor another person, he is able to retract his declaration; according to the Rabbis, once he declared the property ownerless, although he can take possession of it, he is unable to retract the declaration. The Gemara answers: It is different when one declares an item ownerless for a year or a seven-year period, as doing so is uncommon. Since from the outset he limited the duration of ownerless status, clearly he reserved for himself certain rights; therefore, he can retract his declaration.

Reish Lakish said: From the fact that the latter clause is in accordance with the opinion of Rabbi Yosei, the first clause is also in accordance with the opinion of Rabbi Yosei. And in the first clause, this is the reason that one cannot retract his declaration once three days have passed: It is an ordinance instituted by the Sages to ensure that the halakhic status of ownerlessness would not be forgotten. If one could retract his declaration of ownerless status after three days, people would not distinguish between a case where another took possession, where, according to Rabbi Yosei, one is unable to retract the declaration, and a case where another did not take possession, where, according to Rabbi Yosei, one is able to retract the declaration. The result would be that people would mistakenly conclude that ownerless status can always be reversed, even after it was claimed by another. Therefore, the Sages instituted a limit of three days, after which one may not retract his declaration.

The Gemara asks: If so, then let the Sages institute that the item is considered ownerless even from the first day as well and that he cannot retract his declaration at all. Rabba said: The reason that the Sages did not render the item ownerless from the first day is due to the swindlers, who declare the field ownerless in order to render the produce of the field exempt from the requirement of tithing, and then retract that declaration and immediately reclaim the field. Therefore, the Sages instituted that ownerless status takes effect only after three days.

The Gemara asks: The Sages instituted that one cannot retract his declaration of ownerless status once three days have passed. However, by Torah law, isn’t the item ownerless according to Rabbi Yosei, regardless of when he retracted his declaration as long as no other person acquired it?