But Jesus isn't giving just one thing more for the rich young man to do. Jesus is giving the man something impossible for him to do. If he could have sold all of his possessions and given them to the poor, Jesus would have picked something else for him to do that was likewise impossible.
I think what is key here is the invocation of the Ten Commandments... even if only the second tablet. When we read the Ten Commandments, they are not simply a list of things that we should do. They also act as a mirror of our existence and show us how broken our lives are. When Luther explains the Ten Commandments in the Small Catechism, he uses both a positive and negative explanation for each commandment. For instance, take the seventh commandment.
You are not to steal.With this explanation, Christians are not to congratulate ourselves by saying "Look at me, I managed not to take anything at all from my neighbor." The seventh commandment also includes the notion that we are to help our neighbor improve their lot and protect what is theirs. This positive meaning radicalizes the Law for us. It ensures that we cannot keep it because we all too often fail in this light, living in broken relationship with our neighbors.
What is this? Answer:
We are to fear and love God, so that we neither take our neighbors’ money or property nor acquire them by using shoddy merchandise or crooked deals, but instead help them to improve and protect their property and income.
Jesus pulls this positive meaning out for the rich young man. And when he hears it, the young man is incapable of doing it and understands what Jesus says as another thing to do. Instead, Jesus takes him to the edge of his existence, to the place where he believes he cannot go. And confronted with that reality the rich man walks away. He believes it is impossible.
Jesus' act of giving him one thing more to do which is impossible is precisely the way Jesus loves the rich man. He loves him even knowing that the young man cannot do the thing he asks. But the confrontation with impossibility of the Law is not to drive us away from Christ, but precisely the opposite. Convicted by our inability to keep the Law we are to be driven to Christ, that is where Jesus' love takes us... to him... to the impossible existence that we think we cannot live. Jesus' love puts a camel through the eye of the needle.