26 I call the heavens and the earth as witnesses against you this day that you will quickly perish from the land that you are crossing the Jordan to possess. You will not live there long but will certainly be destroyed.

Read Deuteronomy 4:26 Using Other Translations

I call heaven and earth to witness against you this day, that ye shall soon utterly perish from off the land whereunto ye go over Jordan to possess it; ye shall not prolong your days upon it, but shall utterly be destroyed.
I call heaven and earth to witness against you today, that you will soon utterly perish from the land that you are going over the Jordan to possess. You will not live long in it, but will be utterly destroyed.
“Today I call on heaven and earth as witnesses against you. If you break my covenant, you will quickly disappear from the land you are crossing the Jordan to occupy. You will live there only a short time; then you will be utterly destroyed.