Numbers 16:28-30

²⁸And Moses said, “This is how you will know that the Lord has sent me to do all these things that I have done—for I have not done them on my own.

²⁹If these men die a natural death, or if nothing unusual happens, then the Lord has not sent me.

³⁰But if the Lord does something entirely new and the ground opens its mouth and swallows them and all their belongings, and they go down alive into the grave, then you will know that these men have shown contempt for the Lord.”