Omni 1:6

"For the Lord would not suffer, after he had led them out of the land of Jerusalem and kept and preserved them from falling into the hands of their enemies, yea, he would not suffer that the words should not be verified, which he spake unto our fathers, saying that: Inasmuch as ye will not keep my commandments ye shall not prosper in the land."

The Lord will keep his word. He will not let consequences fall away. There are always consequences for our choices, and since these people were not keeping his commandments they did not prosper. He keeps his word.