Matthew 19:5

And said, For this cause shall a man leave father and mother, and shall cleave to his wife: and they twain shall be one flesh?

And said,.... Genesis 2:24 where they seem to be the words of Adam, though here they are ascribed to God, who made Adam and Eve; and as if they were spoken by him, when he brought them together; and which is easily reconciled by observing, that these words were spoken by Adam, under the direction of a divine revelation; showing, that there would be fathers, and mothers, and children; and that the latter, when grown up, would enter into a marriage state, and leave their parents, and cleave to their proper yoke fellows, which relations then were not in being: this therefore being the effect of a pure revelation from God, may be truly affirmed to be said by him. Some think they are the words of Moses the historian; and if they were, as they were delivered by divine inspiration, they may be rightly called the word of God. A note by Jarchi on this text exactly agrees herewith, which is Nk trmwa vdqh

xwr, "the holy Spirit says thus: for this cause shall a man leave father and mother, and shall cleave to his wife"; and not wives: and the phrase denotes that close union between a man and his wife, which is not to be dissolved for every cause, it being stricter than that which is between parents and children; for the wife must be cleaved unto, and father and mother forsaken: not that upon this new relation between man and wife, the former relation between parents and children ceases; nor does this phrase denote an entire separation from them, so as to have the affection alienated from them, or to be disengaged from all duty and obedience to them, and care and regard for them, for the future; but a relinquishing the "house of his father and the bed of his mother", as all the three Targums on the place explain it: that is, he shall quit the house of his father, and not bed and board there, and live with him as before; but having taken a wife to himself, shall live and cohabit with her:

and they twain shall be one flesh; the word "twain" is: not in the Hebrew text in Genesis, but in the Septuagint version compiled by Jews, in the Samaritan Pentateuch, and version, and in the Targum of Jonathan ben Uzziel, who renders, it as here, dx arvybl Nwhywwrt

Nwhyw, "and they two shall be one flesh". This is the true sense, for neither more nor less can possibly be meant; and denotes that near conjunction, and strict union, between a man and his wife, the wife being a part of himself, and both as one flesh, and one body, and therefore not to be parted on every slight occasion; and has a particular respect to the act of carnal copulation, which only ought to be between one man and one woman, lawfully married to each other;

See Gill on "1 Corinthians 6:16".