42:15. I shall now presently try what you are: by the health of Pharao, you shall not depart hence, until your youngest brother come.
42:16. Send one of you to fetch him: and you shall be in prison, till what you have said be proved, whether it be true or false: or else by the health of Pharao you are spies.
Or else by the health of Pharao you are spies... That is, if these things you say be proved false, you are to be held for spies for your lying, and shall be treated as such. Joseph dealt in this manner with his brethren, to bring them by the means of affliction to a sense of their former sin, and a sincere repentance for it.
42:17. So he put them in prison three days.
42:18. And the third day he brought them out of prison, and said: Do as I have said, and you shall live: for I fear God.
42:19. If you be peaceable men, let one of your brethren be bound in prison: and go ye your ways, and carry the corn that you have bought, unto your houses.
42:20. And bring your youngest brother to me, that I may find your words to be true, and you may not die. They did as he had said.
42:21. And they talked one to another: We deserve to suffer these things, because we have sinned against our brother, seeing the anguish of his soul, when he besought us, and we would not hear: therefore is this affliction come upon us.
42:22. And Ruben, one of them, said: Did not I say to you: Do not sin against the boy; and you would not hear me? Behold his blood is required.
42:23. And they knew not that Joseph understood, because he spoke to them by an interpreter.