Ten men with leprosy stand at a distance, as the law required of them, and call out to Jesus for mercy as he passes through a village on the border between Samaria and Galilee. Jesus does not touch them or pronounce them clean on the spot. He tells them simply to go and show themselves to the priests, the step required before a healed person could be officially declared clean.

They are healed as they go, somewhere on the road, before they ever reach the priests.

They Obeyed Before They Had Any Visible Evidence It Worked

Jesus’s instruction assumes a healing that has not yet happened when he gives it. Going to show themselves to priests only made sense for people who were already clean, yet all ten set out toward the priests while still visibly sick, obeying an instruction that had not been confirmed by anything they could see yet.

Nine Kept Moving Toward What They Had Been Told to Do

The nine who do not return are not described as ungrateful in any elaborate sense. They simply continue doing exactly what Jesus told them: going to the priests. Their obedience to the original instruction is, in a sense, complete. It is just missing something else.

One Turned Back Before Finishing the Errand

“One of them, when he saw he was healed, came back, praising God in a loud voice. He threw himself at Jesus’s feet and thanked him, and he was a Samaritan.” This man interrupts his own obedience to the instruction in order to do something the instruction never asked for: return and give thanks, in person, before completing the errand he had been sent on.

Jesus Named the Absence of the Other Nine Directly

“Were not all ten cleansed? Where are the other nine? Has no one returned to give praise to God except this foreigner?” Jesus does not simply accept the one man’s gratitude and move on. He names the gap explicitly, noting that the one who returned was the outsider among the group, not one of the nine who would have had more standing to feel entitled to the healing.

“Then Jesus asked, ‘Were not all ten cleansed? Where are the other nine? Has no one returned to give praise to God except this foreigner?'”
Luke 17:17-18

All ten were healed. Only one came back before doing anything else, and he was the one with the least obvious reason to expect it.