‘But Jesus responded, “He wrote this commandment only as a concession to your hard hearts.”‘ (Mark 10:5 NLT).

THE LAW AND HARD HEARTS
Some Pharisees came to Jesus with a question about divorce. He answered with His own question (as was His habit) whether they knew what Moses wrote in the law concerning divorce. They replied that the Mosaic law permitted divorce. Jesus responded that the law was a “concession” to “hard hearts.”
 
I wonder, wasn’t all the law written because of the hardness of our hearts? For if we could keep the Great Commandment, wouldn’t we have hearts filled with love and therefore no longer require the other laws? Would the one who loves God with all his heart, need to be told not to take the Lord’s name in vain? Would the one who loves their neighbor, need to be instructed not to murder them? If the human heart was not hardened by sin, the written law would have no purpose, for the law of love would already be written on our hearts. Yet, the law was needed because our hearts are hard until the old, sin callous is circumcised by faith in Christ, who is able to give us new and clean hearts filled with love.