Genesis 42:15

42:15 You will be tested in this way: As surely as Pharaoh lives, you will not depart from this place unless your youngest brother comes here.

Genesis 42:19-20

42:19 If you are honest men, leave one of your brothers confined here in prison while the rest of you go and take grain back for your hungry families. 42:20 But you must bring your youngest brother to me. Then your words will be verified and you will not die.” They did as he said.