This Bible contradiction is from the EvilBible.com.
Marriage or cohabitation with a sister denounced
Deuteronomy 27:22 View context
Cursed [be] he that lieth with his sister, the daughter of his father, or the daughter of his mother. And all the people shall say, Amen.
Leviticus 20:17 View context
And if a man shall take his sister, his father's daughter, or his mother's daughter, and see her nakedness, and she see his nakedness; it [is] a wicked thing; and they shall be cut off in the sight of their people: he hath uncovered his sister's nakedness; he shall bear his iniquity.
Abraham married his sister and God blessed the union
Genesis 20:11-12 View context
And Abraham said, Because I thought, Surely the fear of God [is] not in this place; and they will slay me for my wife's sake.
And yet indeed [she is] my sister; she [is] the daughter of my father, but not the daughter of my mother; and she became my wife.