Numbers 16:31

And it came to pass, as he had made an end of speaking all
these things
As soon as he had finished his discourse, which was addressed to the congregation, and, according to Josephus ^F21, after a long prayer to God, which that writer gives at large; immediately so it was,

that the ground clave asunder that [was] under them;
on which they stood, not from any natural cause, as by subterranean volcano, forcibly making their way and bursting the earth, and so getting vent, which has been thought to be the cause of earthquakes; but this was by the immediate hand and almighty power of God, and came to pass just as Moses suggested it would, and as soon as he had uttered his words, which made it the more observable.