Bible Verses About Marriage: Were allowed divorce from, because of hardness of their hearts

When a man taketh a wife, and marrieth her, then it shall be, if she find no favor in his eyes, because he hath found some unseemly thing in her, that he shall write her a bill of divorcement, and give it in her hand, and send her out of his house.

They say unto him, Why then did Moses command to give a bill of divorcement, and to put her away?

He saith unto them, Moses for your hardness of heart suffered you to put away your wives: but from the beginning it hath not been so.