Genesis 42:13-17

And they said, Thy servants are twelve brethren, the sons of one man in the land of Canaan; and, behold, the youngest is this day with our father, and one is not.

And Joseph said unto them, That is it that I spake unto you, saying, Ye are spies:

Hereby ye shall be proved: By the life of Pharaoh ye shall not go forth hence, except your youngest brother come hither.

Send one of you, and let him fetch your brother, and ye shall be kept in prison, that your words may be proved, whether there be any truth in you: or else by the life of Pharaoh surely ye are spies.

And he put them all together into ward three days.