(17) A woman and her daughter.--That is, if a man marries a widow who has a daughter by a former husband, or if he forms an alliance with a woman who has a daughter out of wedlock, he is forbidden to marry also the daughter. But though this prohibition is directed against a peculiar form of polygamy. there can hardly be any doubt that, as the administrators of the law during the second Temple interpreted it, if he married either of them and she died, he could not marry the other any more, and that this prohibition did not apply to cases of illicit commerce. Criminal intercourse with one did not preclude him from marrying the other. For contracting the kind of polygamy here forbidden, the offenders were punished with death by fire. (See Leviticus 20:14.)

Verse 17. - 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).

18:1-30 Unlawful marriages and fleshly lusts. - Here is a law against all conformity to the corrupt usages of the heathen. Also laws against incest, against brutal lusts, and barbarous idolatries; and the enforcement of these laws from the ruin of the Canaanites. God here gives moral precepts. Close and constant adherence to God's ordinances is the most effectual preservative from gross sin. The grace of God only will secure us; that grace is to be expected only in the use of the means of grace. Nor does He ever leave any to their hearts' lusts, till they have left him and his services.Thou shall not uncover the nakedness of a woman and her daughter,.... That is, if a man marries a woman, and she has a daughter, which is the man's daughter-in-law, after the death of his wife he may not marry this daughter; for this daughter is of the same flesh with her mother, who became one flesh with the man she married, and therefore his relation to her daughter is too near to marry her: Jarchi says, if he does not marry the woman, but only deflower her, it is free for him to marry her daughter; but Aben Ezra says, if he has lain with the mother, the daughter is forbidden; however, if he married either of them, the other was forbidden; he could not marry them both, neither in the lifetime of them both, nor after the death of either of them:

neither shalt thou take her son's daughter, or her daughter's daughter, to uncover her nakedness; not any of her granddaughters, either in the line of her son or daughter; that is, might not lie with either of them, or marry them, and much less then marry her own daughter, these being a further remove from her:

for they are her near kinswomen; one or other of them, even every one of them, "the rest" and residue "of her" (r), of her flesh, who together made one flesh with her; and therefore not to be married to her husband, either in her life, or after her death:

it is wickedness: a very great wickedness, abominable in the sight of God, and to be detested by man as vile and impious; it is whoredom, as the Targum of Jonathan renders it.

(r) "reliquiae sunt ipsae", Tigurine version.