Numbers 16:28-30

28Then Moses said, “By this you shall know that the Lord has sent me to do all these works; for I do not act of my own accord.

29If these men die the common death of all mankind or if what happens to everyone happens to them, then [you will know for sure that] the Lord has not sent me.

30But if the Lord creates an entirely new thing, and the ground opens its mouth and swallows them up, along with all that belongs to them, and they descend alive into Sheol (the nether world, the place of the dead), then you will understand that these men have spurned and rejected the Lord!”