John Gill Commentary Luke 4:27

"And there were many lepers in Israel in the time of Elisha the prophet; and none of them was cleansed, but only Naaman the Syrian." — Luke 4:27 (ASV)

And many lepers were in Israel
The leprosy was a disease very common among the Jews; hence those laws concerning it in (Leviticus 13:1–14:57) and it seems by this account, that it was very prevalent,

in the time of Eliseus the prophet ;
that is, the prophet Elisha; who, by the Septuagint, in 1 Kings 19:16
and, in other places, is called "Elisaie": and none of them was cleansed; from their leprosy, by any direction of the prophet,

saving Naaman, the Syrian:
or but Naaman, who was not an Israelite, but a Syrian: he was cleansed and cured of his leprosy, being ordered by Elisha to dip himself seven times in Jordan, which he did, and was healed, (2 Kings 5:14) .