Commentaries:
The scribes and Pharisees, who lived in constant fear of spiritual defilement, ask Jesus why He spends so much time with sinners. His answer is simple: It was His mission to come to this world and to change people's minds so that He can change their lives—to bring them to spiritual health. Recall that all have sinned (Romans 3:23). Every human being—including the scribes and Pharisees—needs the services of the Great Physician. We all need to change our minds so that we experience a positive change in life.
Taken literally, though, Luke 5:32 sounds as if some people need repentance while others do not. However, Jesus never intended His words here to be understood literally. Remember that He is answering the scribes and Pharisees, so what Jesus tells these self-righteous know-it-alls is coated with a heavy layer of sarcasm: "Certainly, you, being so righteous, have no need to repent! I just go where I am most needed!"
The scribes and Pharisees did not consider themselves to be sinners; in fact, they had come nowhere near the point where they could repent. Their hearts were so hard, and they were so convinced of their own goodness that they had closed their minds even to the suggestion that they needed to change in any way. They were blind to their own depravity. However, Jesus went to the ones who knew they were sinners and needed and wanted His help, people He could work with.
Richard T. Ritenbaugh
Repentance: The Genuine Article (Part Four)
Other Forerunner Commentary entries containing Luke 5:31:
Luke 5:36-39
John 6:44