Contradiction with Deuteronomy 25:5
Represents the levirate marriage law, where a brother is encouraged to marry his brother's widow, which could be seen as conflicting with condemning Herod marrying his brother's wife.
Deuteronomy 25:5: If brethren dwell together, and one of them die, and have no child, the wife of the dead shall not marry without unto a stranger: her husband's brother shall go in unto her, and take her to him to wife, and perform the duty of an husband's brother unto her. [her husband's...: or, her next kinsman]
Contradiction with Genesis 38:8
Similar to Deuteronomy 25:5, it discusses the cultural expectation of marrying a brother's widow, which contrasts with John's rebuke of Herod.
Genesis 38:8: And Judah said unto Onan, Go in unto thy brother's wife, and marry her, and raise up seed to thy brother.
Contradiction with 2 Samuel 12:7-8
Nathan points out God's giving of Saul's wives to David, implying divine sanction of such unions, a potential contrast to the condemnation in Matthew 14:4.
2 Samuel 12:7-8: And Nathan said to David, Thou [art] the man. Thus saith the LORD God of Israel, I anointed thee king over Israel, and I delivered thee out of the hand of Saul;
Contradiction with Genesis 20:12
Abraham marries his half-sister, a union that might be considered inappropriate by other standards, yet is presented without condemnation.
Genesis 20:12: 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.