Genesis 42:15-16

15This is how I will test your story. I swear by the life of Pharaoh that you will never leave Egypt unless your youngest brother comes here!

16One of you must go and get your brother. I’ll keep the rest of you here in prison. Then we’ll find out whether or not your story is true. By the life of Pharaoh, if it turns out that you don’t have a younger brother, then I’ll know you are spies.”