Genesis 2:24

Leave his father and his mother. The words of this verse cannot be regarded as a prophetic utterance of Adam, but rather as the words of God Himself. They are part of the declaration made by God at the marriage ceremony (see Matt. 19:4, 5; MB 99). These words express the deepest physical and spiritual unity of man and woman, and hold up monogamy before the world as the form of marriage ordained by God. These words do not recommend a forsaking of filial duty and respect toward father and mother, but refer primarily to the fact that a man’s wife is to be first in his affections and that his first duty is toward her. His love for her is to exceed, though certainly not to supersede, a very proper love for his parents.

They shall be one flesh. The unity of husband and wife is expressed in unmistakable words, existing as they do in a unity of bodies, a community of interests, and a reciprocity of affections. It is a significant fact that Christ uses this very passage in His strong condemnation of divorce (Matt. 19:5).