Thematic Bible: What is not vain

And Moses finished speaking all these words to all Israel; and he said unto them, Set your hearts unto all the words which I protest against you today, to command them unto your children and keep and fulfil all the words of this law. For it is not a vain thing for you because it is your life; and through this thing ye shall prolong your days in the land, which ye shall pass the Jordan to inherit.