Leviticus 18:27

For all these abominations have the men of the land done ,.... The then present inhabitants of Canaan, who dwelt in it before the Israelites came into it; these were guilty of unclean copulations, of incestuous, marriages, of fornication and adultery, and of bestiality and idolatry:

which were before you ; lived in the land before them, had long dwelt there, but now about to be cast out for their sins; and therefore they who were going to succeed them should take warning by them, lest, committing the same sins, they should be cast out likewise:

and the land is defiled ; See Gill on Leviticus 18:25 .