Imamat 18:8

18:8 You must not have sexual intercourse with your father’s wife; she is your father’s nakedness. ¹ 

Ulangan 22:30

22:30 (23:1) ²  A man may not marry ³  his father’s former ⁴  wife and in this way dishonor his father. ⁵ 

[18:8]  ¹ tn Heb “the nakedness of your father she is.” See the note on v. 7 above. This law refers to another wife of the man’s father, who is not that man’s mother. The laws in the Pentateuch sometimes assume the possibility that a man may have more than one wife (cf., e.g., Deut 21:15-17).

[22:30]  ² sn Beginning with 22:30, the verse numbers through 23:25 in the English Bible differ from the verse numbers in the Hebrew text (BHS), with 22:30 ET = 23:1 HT, 23:1 ET = 23:2 HT, 23:2 ET = 23:3 HT, etc., through 23:25 ET = 23:26 HT. With 24:1 the verse numbers in the ET and HT are again the same.

[22:30]  ³ tn Heb “take.” In context this refers to marriage, as in the older English expression “take a wife.”

[22:30]  ⁴ sn This presupposes either the death of the father or their divorce since it would be impossible for one to marry his stepmother while his father was still married to her.

[22:30]  ⁵ tn Heb “uncover his father’s skirt” (so ASV, NASB). This appears to be a circumlocution for describing the dishonor that would come to a father by having his own son share his wife’s sexuality (cf. NAB, NIV “dishonor his father’s bed”).