1,210. Conditionally Gifting a Lulav on Shabbos

Hilchos Shofar, Succah v’Lulav 8:9

All the examples of the four species that have this far been defined as invalid because of various defects or because they were stolen are only invalid for use on the first day of Succos; on subsequent days of the holiday, they are valid. Species that were invalid because of some association with idolatry, or because the esrog is a forbidden form of produce, are invalid both on the first day and on subsequent days.

Hilchos Shofar, Succah v’Lulav 8:10

On the first day of Succos, one cannot fulfill his obligation using a lulav that belongs to another and was borrowed; it must be presented to him as a gift. If the owner gives it to him as a gift with the condition that it be returned, the recipient can use it to fulfill his obligation and then return it because a gift given on such a condition is considered a valid acquisition. If the recipient does not return the lulav, he does not fulfill his obligation because it is tantamount to a stolen lulav. A lulav should not be given to a minor because, under to Torah law, a minor can take possession of something but not transfer it to another. Therefore, the minor returning the lulav would not be considered an effective return. All this applies both to the actual lulav and to the other species that are taken with it. If any of the species is borrowed, one does not fulfill his obligation with it on the first day of Succos.