After Jesus had set his face to go to Jerusalem (Luke 9:51), he multiplied his ministry by sending out the seventy-two on a short-term mission trip (Luke 10). Later, after the seventy-two had returned, Jesus had an encounter with an expert in the law (Jewish law, at least, and perhaps even Roman law).
The law expert wanted to test Jesus, and later he wanted to justify himself. When we want to test Jesus, we are doing what the devil did with Jesus in the wilderness (Matthew 4:1-11). When we want to justify ourselves, we will remain stagnant in our faith and ultimately become idolatrous.
His question was not bad (i.e., it dealt with eternal life), but how he framed it up (What must I do . . . ?) might be indicative of his pride and legalism. The Master Teacher asked the lawyer a question. Jesus is interested in how we read his word. The lawyer knew the answer to the most important part of the law, love God and love neighbor (Deuteronomy 6:1-4 and Leviticus 19:18). For the moment, all sounded good. Jesus challenged him by saying, “Do this and you will live.”
But the lawyer had a question about who should be classified as his neighbor. That answer is next.