Genesis 42:33-34

Then the man, the lord of the country, said to us, ‘By this I will know that you are honest men: Leave one of your brothers here with me, take food for the famine of your households, and be gone. And bring your youngest brother to me; so I shall know that you are not spies, but that you are honest men. I will grant your brother to you, and you may trade in the land.’ ”