Genesis 42:33-34

And the man, the lord of the country, said unto us, Hereby shall I know that ye are true men; leave one of your brethren here with me, and take food for the famine of your households, and be gone: and bring your youngest brother unto me: then shall I know that ye are no spies, but that ye are true men: so will I deliver you your brother, and ye shall traffick in the land.