These twelve Jesus sent forth, and commanded them, saying, Go not into the way of the Gentiles, and into any city of the Samaritans enter ye not: But go rather to the lost sheep of the house of Israel.
-- Matthew 10:5f.
In Luke 17 Jesus himself practices what he preaches in Matthew 10, avoiding Samaria.
He takes the route south from Galilee after his ministry in Galilee, passing through the Valley of Jezreel which runs between Galilee and Samaria from northwest to southeast.
He does this to get over to the Jordan Valley, where John had baptized him like everybody else (Luke 3:21; 4:1) and which runs straight south to Jericho (Luke 18:35). Once in Jericho, he literally goes up to Jerusalem from there (Luke 18:31; 19:28) to meet his fate, a climb of as much as 3,700 feet in elevation.
Note that for their part the Samaritans in Luke's telling also avoid Jesus (Luke 9:52f.), because he's headed to the rival religious center in Jerusalem. The bad feelings are mutual.
But by the time we get to Luke 17 we are met with at least one thankful leper whom Luke says is a Samaritan but Jesus merely calls a foreigner:
On the way to Jerusalem he was passing along between Sama'ria and Galilee. ... "Was no one found to return and give praise to God except this foreigner [ἀλλογενὴς]?"
-- Luke 17:11, 18
Were the ungrateful nine healed lepers in the story also Samaritans?
The text does not say.
Luke does not have the saying found in Matthew, Many are called, but few are chosen (Matthew 20:16; 22:14), but it might not be wrong to say that he is illustrating that in every tribe and tongue most people really suck, but not all of them.
