Genesis 42:17

15By this you shall be tested. By the life of Pharaoh, you shall not go out from here, unless your youngest brother comes here.

16Send one of you, and let him get your brother, and you shall be bound, that your words may be tested, whether there is truth in you, or else by the life of Pharaoh surely you are spies.”

17He put them all together into custody for three days.

18Joseph said to them the third day, “Do this, and live, for I fear God.

19If you are honest men, then let one of your brothers be bound in your prison; but you go, carry grain for the famine of your houses.