Midrash sur Le Lévitique 19:29

1) (Vayikra 19:29) ("Do not profane your daughter to make her a harlot, lest the land fall into harlotry and the land be filled with lewdness.") "Do not profane your daughter to make her a harlot": I might think that (this means that) he (a Cohein) should not give her to a Levite or to an Israelite (in marriage, this being regarded as "profanation" in that she thus becomes unfit to eat terumah); it is, therefore, written "to make her a harlot." Scripture is speaking only of the "profanation" of harlotry.

2) And what is that? One's giving his single daughter to his neighbor, not for the sake of marriage, and, similarly, her giving herself, to this end.

3) "lest the land fall into harlotry": by withholding its fruit. I might think (that this occurs even) if individuals (sin in this regard); it is, therefore, written "and the land be filled with lewdness," and not if individuals (alone sin).