Deuteronomy 27:20

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