Deuteronomy 27:20

“Cursed [be] he that lieth with his father’s wife, etc.] As Reuben did, and which is forbidden (<031808>Leviticus 18:8); because he uncovereth his father’s skirt; (see <052230>Deuteronomy 22:30); and all the people shall say Amen; the tribe of Reuben said this as well as the rest.”

“Compare Joshua 8:32-35. The solemnity was apparently designed only for the single occasion on which it actually took place. Deuteronomy 27:12, Deuteronomy 27:13 The tribes appointed to stand on Gerizim to bless the people all sprang from the two wives of Jacob, Leah and Rachel. All the four tribes which sprang from the handmaids Zilpah and Bilhah are located on Ebal. But in order, as it would seem, to effect an equal division, two tribes are added to the latter from the descendants of the wives, that of Reuben, probably because he forfeited his primogeniture Genesis 49:4; and of Zebulun, apparently because he was the youngest son of Leah. The transaction presents itself as a solemn renewal…”

“27:20 violated his father: See 22:30.”

“Deu 22:30; Gen 35:22, Gen 49:4; Lev 18:8, Lev 20:11; Sa2 16:22; Ch1 5:1; Eze 22:10; Amo 2:7; Co1 5:1 Deuteronomy 27:21”