Genesis 42:14-17

14Joseph said to them, “It is just as I told you: You are spies! 15And this is how you will be tested: As surely as Pharaoh lives, you will not leave this place unless your youngest brother comes here. 16Send one of your number to get your brother; the rest of you will be kept in prison, so that your words may be tested to see if you are telling the truth. If you are not, then as surely as Pharaoh lives, you are spies!”

17And he put them all in custody for three days.