Modern critics pronounce this as being "a difficult and certainly corrupt passage"; but it is only elliptical.
make one?. make [of twain] one flesh? Ref to Pentateuch (Genesis 2:24). App-92.
Yet had He, &c. And therefore could have made more than one wife for Adam.
spirit. Hebrew. ruach. App-9.
And wherefore one? And what [did] that one [Abraham] who [was] seeking. seed of (or from) God? Hebrew. zera. (as in Genesis 21:12. see note there). The logical Ellipsis. must be further supplied: "Was Abraham faithless to Sarah and did he ill-treat her when he took an additional wife? How mach more ought ye to be faithful to your wives? "
one. Refers to Abraham. See Isaiah 51:2.Ezekiel 33:24. Supply the verb "do", as in Ecclesiastes 2:12, and as in Judges 18:8, from Mal 2:18.
take heed. be watchful over.
your. your own.