2 Kings 5:15
And he returned to the man of God, he and all his company, and came, and stood before him: and he said, Behold, now I know that there is no God in all the earth, but in Israel: now therefore, I pray thee, take a blessing of thy servant. And he returned to the man of God, he and all his company, and came, and stood before him: and he said, Behold, now I know that there is no God in all the earth, but in Israel: now therefore, I pray thee, take a blessing of thy servant.
This is part of the story of Naaman's healing through Elisha, toward which the witness of the captive maid had directed him to the power of God. After he submitted to the prophet's directions and was healed of his leprosy, he returned with gratitude to the man of God. On that return he confessed that Israel's God is the only God in all the earth.
The God he confessed is the living God, the Creator. His offer of a costly gift followed the custom of the time, yet Elisha refused to accept payment for the blessing God had mercifully given. His healing of body was accompanied by conversion of spirit.
His honest response to the light he had received made him more worthy of blessing than Israelites whose unbelief and disregard of their privileges closed them to good. His faith stands as an object lesson for those who serve God, showing that God works for those who value His favors and respond to the light given them. Those who faithfully follow what they understand to be their duty receive increased light and are led to the same acknowledgment that there is no other God.
Recognizing God's power through healing leads a person to this acknowledgment, and connection with the Great Physician brings the revelation of God's salvation and the knowledge that there is a God in Israel. The verse expresses the recognition that God is present and powerful in Israel. Applied to times of crisis, when God intervenes against evil He makes it plain that He will uphold His law and vindicate His people.