Their last words will reveal their true priorities. The true secrets of their hearts come out. I knew a man who found out he was dying with cancer and spent his last weeks calling people all over the place apologizing to them.
Priorities tend to change at that time.
The words of this text are the last words of Joshua. He is reminding them of God's faithfulness and their backsliding. The name Joshua and Jesus are the same word in the Greek. Joshua is testifying to how they know God has kept every promise. Nothing he has ever said has not come true.