On one occasion an expert in the law stood up to test Jesus.
“Teacher,” he asked, “what must I do to inherit eternal life?”
“What is written in the Law?” [Jesus] replied. . . .
[The man] answered: “ ‘Love the Lord your God with all your heart and with
all your soul and with all your strength and with all your mind’; and, ‘Love
your neighbor as yourself.’ ”
“You have answered correctly,” Jesus replied. “Do this and you will live.” But
[the man] wanted to justify himself, so he asked Jesus, “And who is my
neighbor?”
In reply Jesus said: “A man was going down from Jerusalem to Jericho, when
he fell into the hands of robbers. They stripped him of his clothes, beat him
and went away, leaving him half dead. A priest happened to be going down
the same road, and when he saw the man, he passed by on the other side.
So too, a Levite, when he came to the place and saw him, passed by on
the other side. But a Samaritan, as he traveled, came [to] where the man was;
and when he saw him, he took pity on him. He went to him and bandaged his
wounds, pouring on oil and wine. Then he put the man on his own donkey,
took him to an inn and took care of him. The next day he took out two silver
coins and gave them to the innkeeper. ‘Look after him,’ he said, ‘and when I
return, I will reimburse you for any extra expense you may have.’
“Which of these three do you think was a neighbor to the man who fell into
the hands of robbers?” [Jesus asked.]
The expert in the law replied, “The one who had mercy on him.”

. What did the Samaritan do that the other passersby did not do?

In the course of a discussion about what it means to love one's neighbor, Jesus tells a parable about a man in need who receives compassionate care from a person who was supposed to be his enemy, a Samaritan.

Explanation:

The context in which Jesus tells this parable is important for understanding what the parable itself means. The Gospel's narrator reveals that the legal expert talking to Jesus is attempting "to justify himself" when he asks Jesus, "And who is my neighbor?" His intention, therefore, is to limit the understanding of who rightly can be considered his neighbor, to limit the range of people whom he must love. The parable responds by expanding the notion of who qualifies as a person's neighbor.

The parable itself is a story of great compassion coming from an unlikely source. Jesus certainly presents the injured man as a Jew, yet leaders among his own people--the priest and the Levite--refuse to help him. These two passersby are religious figures, and their associations with the Jerusalem temple make them connected to the heart of Jewish identity and piety. The Samaritan who appears on the scene is out of place in Judea, on a road between Jerusalem and Jericho. Because most Samaritans and Jews held deep-seated resentments against the other group, the compassion and actions of the Samaritan in the parable are surprising. He reflects the lengths to which love will go. He treats the injured man not as an enemy but as a neighbor, as one of his own.