מדרש על ויקרא 14:34

1) (Vayikra 14:34) ("When you come to the land of Canaan, which I give to you for a possession, and I put a plague-spot of leprosy in a house of the land of your possession,") "When you come": I might think (that this applies) when they come to trans-Jordan; it is, therefore, written "to the land" — to the distinctive land (of Israel).

2) "which I give to you": I might think (that this applies) when they come to Ammon and Moav; it is, therefore, written "which I give to you," and not Ammon and Moav.

3) "for a possession": (not) until they conquer it. Whence is it derived that if they conquered it, but did not yet divide it (among the tribes); if they divided it (among the families), but did not yet apportion it into patrimonies and each did not clearly recognize his own — I might think that they would be subject to plague-spot tumah; it is, therefore, written (Vayikra 14:35) "Then he whose house it is shall come" — each must recognize what is his.