John Calvin Commentary Joshua 24:22

"And Joshua said unto the people, Ye are witnesses against yourselves that ye have chosen you Jehovah, to serve him. And they said, We are witnesses." — Joshua 24:22 (ASV)

And Joshua said to the people, etc. We now understand what the goal was that Joshua had aimed at until now. It was not to terrify the people and make them fall away from their religion, but to make the obligation more sacred by their choosing his government of their own accord and committing themselves to his guidance, so that they might live under his protection.

They acknowledge, therefore, that their own conscience will accuse them and hold them guilty of perfidy if they prove unfaithful. But although they were not insincere in declaring that they would be witnesses to their own condemnation, it is still obvious from the Book of Judges how easily the remembrance of this promise faded away. For when the older ones among them had died, they quickly turned aside to various superstitions. By this example we are taught how multifarious are the fallacies that occupy the minds of people, and how tortuous the recesses in which they hide their hypocrisy and folly, while they deceive themselves with false confidence.