Leviticus 20:19

No civil punishment, on the other hand, to be inflicted by the magistrate or by the community generally, was ordered to follow marriage with an aunt, the sister of father or mother (Lev 20:19, cf. Lev 18:12-13), with an uncle's wife (Lev 20:20, cf. Lev 18:4), or with a sister-in-law, a brother's wife (Lev 20:21, cf. Lev 18:16). In all these cases the threat is simply held out, "they shall bear their iniquity," and (according to Lev 20:20, Lev 20:21) "die childless;" that is to say, God would reserve the punishment to Himself (see at Lev 18:14). In the list of punishments no reference is made to intercourse with a mother (Lev 18:7) or a granddaughter (Lev 18:10), as it was taken for granted that the punishment of death would be inflicted in such cases as these; just as marriage with a daughter or a full sister is passed over in the prohibitions in ch. 18.

The laws which before were made are in this chapter repeated and penalties annexed to them, that those who would not be deterred from sin by the fear of God might be deterred from it by the fear of punishment. If we will not avoid such and such practices because the law has made them sin (and it is most acceptable when we go on that principle of religion), surely we shall avoid them when the law has made them death, from a principle of self-preservation. In this chapter we have, I. Many particular crimes that are made capital. I. Giving their children to Moloch (Lev 20:1-5). 2. Consulting witches (Lev 20:6, Lev 20:27). 3. Cursing parents (Lev 20:9). 4. Adultery (Lev 20:10). 5. Incest (Lev 20:11, Lev 20:12, Lev 20:14, Lev 20:17, Lev 20:19-21). 6. Unnatural lusts (Lev 20:13, Lev 20:15, Lev 20:16, Lev 20:18). II. General commands given to be holy (Lev 20:7, Lev 20:8, Lev 20:22-26).