30 But if the Lord make  a new thing, and the earth open her mouth, and swallow them up, with all that appertain unto them, and they go down quick into the pit; then ye shall understand that these men have provoked the Lord.
30 But if the Lord brings about something totally new, and the earth opens its mouth and swallows them, with everything that belongs to them, and they go down alive into the realm of the dead, then you will know that these men have treated the Lord with contempt."
English Standard Version
30 But if the Lord creates something new, and the ground opens its mouth and swallows them up with all that belongs to them, and they go down alive into Sheol, then you shall know that these men have despised the Lord."
30 But if God does something unprecedented - if the ground opens up and swallows the lot of them and they are pitched alive into Sheol - then you'll know that these men have been insolent with God."
New King James Version
30 But if the Lord creates a new thing, and the earth opens its mouth and swallows them up with all that belongs to them, and they go down alive into the pit, then you will understand that these men have rejected the Lord."
New Living Translation
30 But 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 ."
The seventy elders of Israel attend Moses. It is our duty to do what we can to countenance and support lawful authority when it is opposed. And those who would not perish with sinners, must come out from among them, and be separate. It was in answer to the prayer of Moses, that God stirred up the hearts of the congregation to remove for their own safety. Grace to separate from evil-doers is one of the things that accompany salvation. God, in justice, left the rebels to the obstinacy and hardness of their own hearts. Moses, by Divine direction, when all Israel were waiting the event, declares that if the rebels die a common death, he will be content to be called and counted an imposter. As soon as Moses had spoken the word, God caused the earth to open and swallow them all up. The children perished with their parents; in which, though we cannot tell how bad they might be to deserve it, or how good God might be otherwise to them; yet of this we are sure, that Infinite Justice did them no wrong. It was altogether miraculous. God has, when he pleases, strange punishments for the workers of iniquity. It was very significant. Considering how the earth is still in like manner loaded with the weight of man's sins, we have reason to wonder that it does not now sink under its load. The ruin of others should be our warning. Could we, by faith, hear the outcries of those that are gone down to the bottomless pit, we should give more diligence than we do to escape for our lives, lest we also come into their condemnation.