Mattityahu 19:7-9

Orthodox Jewish Bible

⁷ They say to him, Why then did Moshe Rabbenu give the mitzvah to give the get, the sefer keritut, and send her away?

⁸ He says to them, Moshe, because of your hardness of heart, permitted you to give the get to your wives; but from bereshis (in the beginning), however, it was not so.

⁹ But I [Moshiach] say to you that whoever, the case of zenut (fornication) being excepted, gives the get to his wife and marries another, is guilty of niuf (adultery).