Numbers 16:28-30

28Then Moses said, “This is how you will know that the Lord sent me to do all these things and that it was not of my own will:

29If these men die naturally as all people would, and suffer the fate of all, then the Lord has not sent me.

30But if the Lord brings about something unprecedented, and the ground opens its mouth and swallows them along with all that belongs to them so that they go down alive into Sheol, then you will know that these men have despised the Lord.”