John Gill Bible Commentary

And the man that lieth with his father's wife,.... Whether she be his mother, or another woman, as the Targum of Jonathan; that is, whether she is his own mother, or a stepmother, or whether he did this in the lifetime of his father, or after his death, or whether she was betrothed or married, it mattered not; according to the Jewish tradition (d), this is a breach of the law, Lev 18:8; and a man guilty of this hath uncovered his father's nakedness; and which is a foul and shameful piece of wickedness; the penalty follows: both of them shall be put to death; by casting stones on them, as the Targum of Jonathan adds; for, as before observed, wherever the following phrase: their blood shall be upon them, is used, stoning is meant; and so, according to the Misnah (e), all those were to be stoned, after mentioned, of whom this phrase is used. (d) Misn. ut supra, (Sanhedrin, c. 7.) sect. 4. (e) lbid.