Malachi 2:16

“If a man marries a woman who becomes displeasing to him because he finds something indecent about her, and he writes her a certificate of divorce, gives it to her and sends her from his house, and if after she leaves his house she becomes the wife of another man, and her second husband dislikes her and writes her a certificate of divorce, gives it to her and sends her from his house, or if he dies, then her first husband, who divorced her, is not allowed to marry her again after she has been defiled. That would be detestable in the eyes of the Lord. You must not bring sin upon the land the Lord your God is giving you as an inheritance.”

Deals with divorce in the Old Testament law.

“So they are no longer two, but one flesh. Therefore what God has joined together, let no one separate.”

Jesus' teaching on the permanence of marriage.

“To the married I give this command (not I, but the Lord): A wife must not separate from her husband. But if she does, she must remain unmarried or else be reconciled to her husband. And a husband must not divorce his wife.”

Pauline teaching on marriage and divorce, emphasizing reconciliation.

“But I tell you that anyone who divorces his wife, except for sexual immorality, makes her the victim of adultery, and anyone who marries a divorced woman commits adultery.”

Jesus' stricter interpretation of divorce, focusing on adultery.

“"Rebuke your mother, rebuke her, for she is not my wife, and I am not her husband. Let her remove the adulterous look from her face and the unfaithfulness from between her breasts.”

Metaphorical language of covenant unfaithfulness as marital unfaithfulness.