| Gill's Exposition of the Entire Bible And thou shalt not uncover the nakedness of thy mother's sister, nor of thy father's sister,.... An aunt either by mother or father's side, against which the law is, Leviticus 18:13, for he uncovereth his near kin; as an aunt is to a man, and so an uncle to a woman, and both equally criminal; for it is a rule that holds good in all those cases, though not expressed, that what is binding upon one sex is upon the other, being in the same degree of relation, whether of consanguinity or affinity: they shall bear their iniquity; "both" of them, as the Vulgate Latin version, the man and his aunt, and so a woman and her uncle: the guilt of their sin shall be upon them, and the punishment of it be inflicted on them; either they should be cut off from their people, as before, or be childless, as in the following instances.
Keil and Delitzsch Biblical Commentary on the Old TestamentNo 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 (Leviticus 20:19, cf. Leviticus 18:12-13), with an uncle's wife (Leviticus 20:20, cf. Leviticus 18:4), or with a sister-in-law, a brother's wife (Leviticus 20:21, cf. Leviticus 18:16). In all these cases the threat is simply held out, "they shall bear their iniquity," and (according to Leviticus 20:20, Leviticus 20:21) "die childless;" that is to say, God would reserve the punishment to Himself (see at Leviticus 18:14). In the list of punishments no reference is made to intercourse with a mother (Leviticus 18:7) or a granddaughter (Leviticus 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.
Geneva Study BibleAnd thou shalt not uncover the nakedness of thy mother's sister, nor of thy father's sister: for he uncovereth his near kin: they shall bear their iniquity.
King James Translators' Notesuncovereth: Heb. hath made naked
Matthew Henry's Concise Commentary20:10-27 These verses repeat what had been said before, but it was needful there should be line upon line. What praises we owe to God that he has taught the evil of sin, and the sure way of deliverance from it! May we have grace to adorn the doctrine of God our Saviour in all things; may we have no fellowship with unfruitful works of darkness, but reprove them.
Matthew Henry's Whole Bible CommentaryVerses 10-21 Sins against the seventh commandment are here ordered to be severely punished. These are sins which, of all others, fools are most apt to make a mock at; but God would teach those the heinousness of the guilt by the extremity of the punishment that would not otherwise be taught it. I. Lying with another man's wife was made a capital crime. The adulterer and the adulteress that had joined in the sin must fall alike under the sentence: they shall both be put to death, v. 10. Long before this, even in Job's time, this was reputed a heinous crime and an iniquity to be punished by the judges, Job 31:11. It is a presumptuous contempt of an ordinance of God, and a violation of his covenant, Prov. 2:17. It is an irreparable wrong to the injured husband, and debauches the mind and conscience of both the offenders as much as any thing. It is a sin which headstrong and unbridled lusts hurry men violently to, and therefore it needs such a powerful restraint as this. It is a sin which defiles a land and brings down God's judgments upon it, which disquiets families, and tends to the ruin of all virtue and religion, and therefore is fit to be animadverted upon by the conservators of the public peace: but see Jn. 8:3-11. II. Incestuous connections, whether by marriage or not. 1. Some of them were to be punished with death, as a man's lying with his father's wife, v. 11. Reuben would have been put to death for his crime (Gen. 35:22) if this law had been then made. It was the sin of the incestuous Corinthian, for which he was to be delivered unto Satan, 1 Co. 5:1, 5. A man's debauching his daughter-in-law, or his mother-in-law, or his sister, was likewise to be punished with death, v. 12, 14, 17. 2. Others of them God would punish with the curse of barrenness, as a man's defiling his aunt, or his brother's wife (v. 19-21): They shall die childless. Those that keep not within the divine rules of marriage forfeit the blessings of marriage: They shall commit whoredom, and shall not increase, Hos. 4:10. Nay it is said, They shall bear their iniquity, that is, though they be not immediately cut off by the hand either of God or man for this sin, yet the guilt of it shall lie upon them, to be reckoned for another day, and not be purged with sacrifice or offering. III. The unnatural lusts of sodomy and bestiality (sins not to be mentioned without horror) were to be punished with death, as they are at this day by our law, v. 13, 15, 16. Even the beast that was thus abused was to be killed with the sinner, who was thereby openly put to the greater shame: and the villany was thus represented as in the highest degree execrable and abominable, all occasions of the remembrance or mention of it being to be taken away. Even the unseasonable use of the marriage, if presumptuous, and in contempt of the law, would expose the offenders to the just judgment of God: they shall be cut off, v. 18. For this is the will of God, that every man should possess his vessel (and the wife is called the weaker vessel) in sanctification and honour, as becomes saints. | 
