Moses has presented all the terms of the second covenant to the people (4: 44–26: 19; 28). He now summons them to ratify it
Having called Israel to ratify the covenant, Moses reminds Israel, once more, of the Exodus from Egypt and explains that the reason why God allowed Israel to wander in the desert for forty years was to teach them their ways, for there were no other means for them to learn and accept this truth.
These experiences in the desert should be passed on from one generation to the next, to help Israel remain faithful to God. Moses wants the wandering in the wilderness to be seen in its proper supernatural context: God did not act simply to reward or punish the generation of the Exodus: he wanted that experience to serve as an example for later generations that did not live the Exodus. Thus, the passing on of the traditions becomes a key element in the passing on of the faith in the one true God; a lesson Israel will be quick to forget with disastrous consequences.
So it is with us, today. As Catholics, we must always hold fast to the truth of the faith, to the testimony of the saints that have come before us and we must strive to teach our children the truth of the Catholic faith, lest God treats us the way he treated the Churches he had spoken to in the Book of Revelation.