Genesis 42:18-20

On the third day, Yosef said to them, "Do what I say, and stay alive, for I fear God.

If you are upright men, let one of your brothers remain incarcerated in the prison you're being kept in, while you go and carry grain back to relieve the famine in your homes.

But bring your youngest brother to me. In this way your statements will be verified, and you won't die." So they did it.