New Revised Standard Version
They said to him, “Why then did Moses command us to give a certificate of dismissal and to divorce her?”

Contemporary English Version
The Pharisees asked Jesus, "Why did Moses say a man could write out divorce papers and send his wife away?"

New American Bible
They said to him, “Then why did Moses command that the man give the woman a bill of divorce and dismiss [her]?”

Douay-Rheims Bible
They say to him: Why then did Moses command to give a bill of divorce, and to put away?

They say to him: Why then did Moses command to give a bill of divorce, and to put away?

Why.

Matthew 5:31 And it hath been said, Whosoever shall put away his wife, let him give her a bill of divorce.

Deuteronomy 24:1-4 If a man take a wife, and have her, and she find not favour in his eyes, for some uncleanness: he shall write a bill of divorce, and shall give it in her hand, and send her out of his house. . . .

Isaiah 50:1 Thus saith the Lord: What is this bill of the divorce of your mother, with which I have put her away? or who is my creditor, to whom I sold you: behold you are sold for your iniquities, and for your wicked deeds have I put your mother away.

Jeremiah 3:8 That because the rebellious Israel had played the harlot, I had put her away, and given her a bill of divorce: yet her treacherous sister Juda was not afraid, but went and played the harlot also herself.

Mark 10:4 Who said: Moses permitted to write a bill of divorce and to put her away.

and to.

Matthew 1:19 Whereupon Joseph her husband, being a just man, and not willing publicly to expose her, was minded to put her away privately.

Malachi 2:16 When thou shalt hate her put her away, saith the Lord, the God of Israel: but iniquity shalt cover his garment, saith the Lord of hosts, keep your spirit, and despise not.