"Teacher, what shall I do to inherit eternal life?" (Luke 10:25)
He came asking what he had to do. And Jesus, at the end of the whole exchange, having told him a story that dismantled his entire framework, sends him away with a thing to do. Which is strange, and hard to fully resolve, because we know, and Paul will spend his life saying, that you cannot earn this. Not by loving your neighbor, not by loving God, not by anything. It is a gift, it is grace, it is not of works, so that no one may boast. So why does Jesus give him an assignment?
Because the lawyer was not actually asking about salvation. He was asking for a boundary. He wanted to know the size of the debt so he could pay it and be done, and Jesus refused to give him a number and instead handed him a life. Go and do likewise, and keep doing it, and you will find that it does not end, and that you cannot finish it, and one day you will stop trying to.
And that is the day you will understand grace. Not before. Not from a book. From a ditch on the Jericho road, with your hands full of someone else's blood, realizing you are never going to get to the bottom of this. The command was never a ladder to climb to God. It was the long road on which a self-justifying man finally runs out of self, and discovers that the thing he was trying to earn had been a gift the entire time.