Jamieson, Fausset and Brown on 2 Kings 5:15-16

15-16. he returned to the man of God--After the miraculous cure, Naaman returned to Elisha, to whom he acknowledged his full belief in the sole supremacy of the God of Israel and offered him a liberal reward. But to show that he was not actuated by the mercenary motives of the heathen priests and prophets, Elisha, though he accepted presents on other occasions (2Ki 4:42), respectfully but firmly declined them on this, being desirous that the Syrians should see the piety of God's servants, and their superiority to all worldly and selfish motives in promoting the honor of God and the interests of true religion.