Malachi 2:15

And did not he make one? - One of each kind, Adam and Eve. Yet had he the residue of the Spirit, he could have made millions of pairs, and inspired them all with living souls. Then wherefore one? He made one pair from whom all the rest might proceed, that he might have a holy offspring; that children being a marked property of one man and one woman, proper care might be taken that they should be brought up in the discipline of the Lord. Perhaps the holy or godly seed, זרע אלהים zera Elohim, a seed of God, may refer to the Messiah. God would have the whole human race to spring from one pair, that Christ, springing from the same family, might in his sufferings taste death for every man; because he had that nature that was common to the whole human race. Had there been several heads of families in the beginning, Jesus must have been incarnated from each of those heads, else his death could have availed for those only who belonged to the family of which he was incarnated. Take heed to your spirit - Scrutinize the motives which induce you to put away your wives.

And did not He - , God, of whom he had spoken as the witness between man and his wife, “make one,” namely, Adam first, to mark the oneness of marriage and make it a law of nature, appointing “that out of man (created in His own image and similitude), woman should take her beginning, and, knitting them together, did teach that it should never be lawful to put asunder those, whom He by matrimony had made one?” “Between those two, and consequently between all other married, to be born from them, He willed that there should be one indivisible union, for Adam could be married to no other save Eve, since no other had been created by God, nor could Eve turn to any other man than Adam, since there was no other in the world. ‘Infringe not then this sanction of God, and unity of marriage, and degenerate not from your first parents, Adam and Eve.’” “If divorce had been good, Jesus says, God would not have made one man and one woman, but, having made one Adam, would have made two women, had He meant that he should cast out the one, bring in the other; but now by the mode of creation, He brought in this law, that each should have, throughout, the wife which he had from the beginning. This law is older than that about divorce, as much as Adam is older than Moses.” Yet had he the residue of the spirit - Gen 2:7, “the breath of life, which He breathed into Adam, and man became a living soul.” All the souls, which God would ever create, are His, and He could have called them into being at once. Yet in order to designate the unity of marriage, He willed to create but one. So our Lord argues against divorce Mat 19:4-6, “Have ye not read, that He which made them at the beginning, made them male and female?” They both together are called “one man” Gen 1:27, and, therefore, should be of one mind and spirit also, the unity of which they ought faithfully to preserve. And wherefore one? […]