Whether it was lawful to divorce a wife under the Mosaic law?

Objections

Objection 1 : It would seem that it was lawful to divorce a wife under the Mosaic law. For one way of giving consent is to refrain from prohibiting when one can prohibit. It is also unlawful to consent to what is unlawful. Since then the Mosaic law did not forbid the putting away of a wife and did no wrong by not forbidding it, for "the law . . . is holy" (Rm. 7:12), it would seem that divorce was at one time lawful.
Objection 2 : Further, the prophets spoke inspired by the Holy Ghost, according to 2 Pt. 1:21. Now it is written (Malachi 2:16): "When thou shalt hate her, put her away." Since then that which the Holy Ghost inspires is not unlawful, it would seem that it was not always unlawful to divorce a wife.
Objection 3 : Further, Chrysostom [*Hom. xxxii in the Opus Imperfectum falsely ascribed to St. John Chrysostom] says that even as the apostles permitted second marriages, so Moses allowed the bill of divorce. But second marriages are not sinful. Therefore neither was it sinful under the Mosaic law to divorce a wife.
Objection 4 : On the contrary, our Lord said (Mt. 19:8) that Moses granted the Jews the bill of divorce by reason of the hardness of their heart. But their hardness of heart did not excuse them from sin. Neither therefore did the law about the bill of divorce.
Objection 5 : Further, Chrysostom says [*Hom. xxxii in the Opus Imperfectum falsely ascribed to St. John Chrysostom] that "Moses, by granting the bill of divorce, did not indicate the justice of God, but deprived their sin of its guilt, for while the Jews acted as though they were keeping the law, their sin seemed to be no sin."