2,747. Declaring Real Estate Ownerless

Hilchos Nedarim 2:16

If someone declares real estate ownerless, the first to come and establish ownership acquires it. Under Biblical law, if one declares property ownerless in front of even one person, it becomes ownerless and he need not tithe its produce, as we shall see IY”H in Hilchos Trumah. Under rabbinic law, property isn’t rendered ownerless until one declares it in front of three people; this is so that one of them can acquire the property and the other two can serve as witnesses. If a person says, “This is ownerless, and this,” there’s a doubt as to whether the second thing is rendered ownerless. If he says, “This is like this” or “and also this,” then he has related the second thing to the first, so it is certainly ownerless.

Hilchos Nedarim 2:17

If someone declares his field ownerless and no one else takes possession of it, he may retract for the first three days. After three days, he may no longer retract unless he is the first to acquire the property. In this he’s like one acquiring ownerless property, just like anybody else.