Luke 10:29-37 (ESV)
But he, desiring to justify himself, said to Jesus, "And who is my neighbor?"  Jesus replied, "A man was going down from Jerusalem to Jericho, and he fell among robbers, who stripped him and beat him and departed, leaving him half dead.  Now by chance a priest was going down that road, and when he saw him he passed by on the other side.  So likewise a Levite, when he came to the place and saw him, passed by on the other side.  But a Samaritan, as he journeyed, came to where he was, and when he saw him, he had compassion.  He went to him and bound up his wounds, pouring on oil and wine. Then he set him on his own animal and brought him to an inn and took care of him.  And the next day he took out two denarii and gave them to the innkeeper, saying, 'Take care of him, and whatever more you spend, I will repay you when I come back.'  Which of these three, do you think, proved to be a neighbor to the man who fell among the robbers?"  He said, "The one who showed him mercy." And Jesus said to him, "You go, and do likewise."
Desiring to justify himself, off to a bad start there. It is our natural inclination. At times I suppose it is necessary. It is one of those things I think I had to learn the hard way. Growing up, about the worst thing I could do was try to justify anything I had done wrong. My parents just didn’t like excuses. I was best off throwing myself at their mercy, which often seemed on short supply. The world likes excuses. They like a justification. Still at times, I think it still best to plead the fifth and ask for mercy. The world has little of that. It is possible to justify yourself to your neighbor. Not to God.
Where God is concerned our justification is nothing. The only justification is that of his son declaring us innocent. It is the only justification that works.
But the Lawyer needs to justify himself because he has not loved God or neighbor as he should. He instantly knows this and tries to find wiggle room in the definition of neighbor. This is what lawyers do, they try to find loopholes in definitions. He will not be justified by the law.
The only hope is mercy. Mercy. So Jesus shows us mercy. Go and do likewise is the final thing Jesus says. This is like backhanded gospel in the form of an imperative. Go and do likewise, that is show mercy. It is quite incredible. Jesus is saying you are now in the drivers seat. You are now in a position to show mercy. We weren’t before, because mercy had not been shown to us. But now mercy is shown to us, and we are put in that position to then show mercy.