Leviticus 18:17 - Exposition

The ninth form of incest prohibited is intercourse with a stepdaughter, or step-granddaughter, or mother-in-law. The expression made use of, Thou shalt not uncover the nakedness of a woman and her daughter, covers the case of a man's own daughter, and it is singular that it is only in this incidental manner that it is specifically named. But it has been already disposed of by the general command, None of you shall approach to any that is near of kin to him, to uncover their nakedness. The daughter being nearest of kin, this command was sufficient without further specification. The niece and probably the wife's sister are forbidden by the same general rule (see following note).