Jesus was not a theoretician. He did not dispense a lot of ideas and leave His followers to sort out their application. His goal was never to leave behind a great catalogue of sermons. Yes, Jesus was a great teacher, but He never wanted people to make a list of things He said and then debate His teaching points. In other words, Jesus' goal was not to teach and leave us to figure out what to do next. Jesus acted and taught with action in mind so He could teach people how to act.
Jesus often did His teaching with actions, which said more than any sermon ever could. Take the story of Zacchaeus, the little tax collector from Jericho was was too short to see Jesus, so he climbed a tree. Jesus could have turned up in Jericho, preached a sermon on repentance, and then left. But instead of preaching that kind of sermon, He saw a guy in a tree and invited Himself to his home. Some of the the people around Jesus were disturbed that Jesus would enter the home of a low life scumbag like Zacchaeus, a tax collector.
But during the course of this visit, Zacchaeus stands up and says:
"Look, Lord! Here and now I give half of my possessions to the poor, and if I have cheated anybody out of anything, I will pay back four times the amount." Jesus said to him, "Today salvation has come to this house, because this man, too, is a son of Abraham. For the Son of Man came to seek and to save what was lost" (Luke 19:8-10).
The actions of Jesus in Jericho speak so much more loudly than any sermon ever could. He chose one of the worst guys in Jericho, a Chief Tax Collector, went to his house, spent time with him, ate with him, and probably had some good conversation. Zacchaeus knew about Jesus, otherwise he wouldn't have been climbing a tree to get a better look at Him. I don't imagine that Jesus really had to say loads and loads. But in the course of the visit Zacchaeus spontaneously turned away from all his corrupt ways and decided to give money away and pay back the folks he had cheated.
There is no real sermon recorded by Luke. All Jesus says is, 'Salvation has arrived in this house. Zacchaeus is a son of Abraham, a child of faith.' Not much in the way of sermons. But the last part of what Jesus says is the best: 'See this everybody - this is exactly why I came. I came so that people who are far from God like Zacchaeus can come close to God. This is my purpose.'
Jesus, the Man of Action, demonstrates the heart of the Good News - that God wants to come live near us and in us and have us be close to Him. Very literally, God asked Zacchaeus to let Him into his life. When Zacchaeus let that happen, Jesus showed everyone the result - a drastically changed life. Jesus left a reminder for the people of Jericho in the form of Zacchaeus' new way of life, a concrete reminder that God changes lives. In my opinion that is much better than any sermon on repentance than Jesus could have ever preached.