Genesis 42:20 (KJV)

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.

And Joseph said unto them the third day, This do, and live; for I fear God:

If ye be true men, let one of your brethren be bound in the house of your prison: go ye, carry corn for the famine of your houses:

And they said one to another, We are verily guilty concerning our brother, in that we saw the anguish of his soul, when he besought us, and we would not hear; therefore is this distress come upon us.

And Reuben answered them, saying, Spake I not unto you, saying, Do not sin against the child; and ye would not hear? therefore, behold, also his blood is required.

And they knew not that Joseph understood them; for he spake unto them by an interpreter.

And he turned himself about from them, and wept; and returned to them again, and communed with them, and took from them Simeon, and bound him before their eyes.

Then Joseph commanded to fill their sacks with corn, and to restore every man's money into his sack, and to give them provision for the way: and thus did he unto them.