Matthew 19:7
Why then,” they asked, “did Moses command that a man give his wife a certificate of divorce and send her away?”
8 Jesus replied, “Moses permitted you to divorce your wives because your hearts were hard. But it was not this way from the beginning. 9I tell you that anyone who divorces his wife, except for sexual immorality, and marries another woman commits adultery.”
People use this to claim that the torah of YAH wasn't perfect. Then they use that example to make the same case for monogamy only, and pretty much everything else they don't like or agree with.
It's an easy case to break. Simply ask them - where in the "Old Testament" does it say a man can send away his wife for any reason?
There is a process detailed in Deut 24:1 - and the reason implies sexual in nature - therefore - Yeshua was teaching torah. Therefore, whatever commandment Moses gave specifically to the Israelites in the wilderness was not the written word of YAH - but an oral commandment (concession because of the hardness of their hearts - for they were rebellious, stubborn, and some even tried to have Moses himself killed). The perfect Torah of YAH is very clear, and God in the flesh pointed the people back to the Word of God.