Matthew 19:8

Tertullian Against Marcion Book IV

There, while prohibiting divorce, He has given us a solution of this special question respecting it: "Moses," says He, "because of the hardness of your hearts, suffered you to give a bill of divorcement; but from the beginning it was not so"[1325]

Tertullian On Monogamy

So true, moreover, is it that divorce "was not from the beginning," that among the Romans it is not till after the six hundredth year from the building of the city that this kind of "hard-heartedness"[81]

Pseudo-Cyprian Of the Discipline and Advantage of Chastity

For both her own husband belongs to the woman, for the reason that besides him she may know no other; and the woman is given to the man for the purpose that, when that which had been his own had been yielded to him, he should seek for nothing belonging to another.[5]

Clementine Homily III

`Moses gave you commandments according to your hard-heartedness; for from the beginning it was not so: for He who created man at first, made him male and female.'[53]

Origen Commentary on Matthew Book XIV

For it is not necessaryfor adultery or any such great indecency to write a bill of divorcement and give it into the hands ofthe wife; but indeed perhaps Moses called every sin an unseemly thing, on the discovery of which bythe husband in the wife, as not finding favour in the eyes of her husband, the bill of divorcement iswritten, and the wife is sent away from the house of her husband; "but from the beginning it hath notbeen so."[194]