49 Faustus makes a most groundless statement when he accuses the four women of quarreling like abandoned characters for the possession of their husband. Where Faustus read this I know not, unless it was in his own heart, as in a book of impious delusions, in which Faustus himself is seduced by that serpent with regard to whom the apostle feared for the Church, which he desired to present as a chaste virgin to Christ; lest, as the serpent had deceived Eve by his subtlety, so he should also corrupt their minds by turning them away from the simplicity of Christ. The Manichæans are so fond of this serpent, that they assert that he did more good than harm.
From him Faustus must have got his mind corrupted with the lies instilled into it, which he now reproduces in these infamous calumnies, and is even bold enough to put down in writing. It is not true that one of the handmaids carried off Jacob from the other, or that they quarreled about possessing him. There was arrangement, because there was no licentious passion; and the law of conjugal authority was all the stronger that there was none of the lawlessness of fleshly desire. His being hired by one of his wives proves what is here said, in plain opposition to the libels of the Manichæans.
Why should one have hired him, unless by the arrangement he was to have gone in to the other? It does not follow that he would never have gone in to Leah unless she had hired him. He must have gone to her always in her turn, for he had many children by her; and in obedience to her he had children by her hand-maid, and afterwards, without any hiring, by herself. On this occasion it was Rachel's turn, so that she had the power so expressly mentioned in the New Testament by the apostle, "The husband has not power over his own body, but the wife." Rachel had a bargain with her sister, and, being in her sister's debt, she referred her to Jacob, her own debtor.
For the apostle uses this figure when he says, "Let the husband render unto the wife what is due." Rachel gave what was in her power as due from her husband, in return for what she had chosen to take from her sister.
Source: Reply to Faustus the Manichaean (New Advent)