Naaman was not just any military leader. He was the army commander of the king of Aram and a war hero who had brought victory to Aram (2 Kgs 5:1). In such a prestigious position, Naaman was very wealthy (see 2 Kgs 5:5). Naaman was among the elite. He was top gun.
Elisha was an extrovert. He worked many miracles, usually with a flair. However, when Naaman came to Elisha to be healed of leprosy, Elisha did not come out to see, talk to, or pray with Naaman (2 Kgs 5:10-11). Naaman felt snubbed and angry (2 Kgs 5:12).
The rationale for Elisha's uncharacteristic behavior may have been to give Naaman the opportunity to humble himself. When we humble ourselves, we open the door to God and to healing, for the Lord "is stern with the arrogant but to the humble He shows kindness" (1 Pt 5:5). When Naaman swallowed his pride and listened to Elisha and the advice even of his servants, he was healed (2 Kgs 5:14).
Jesus tried a similar approach with His hometown folk. He bluntly told them they were depriving themselves of God's graces because they did not accept His prophets (Lk 4:24-27). They could have humbled themselves, accepted correction from Jesus, and repented. Instead, they tried to throw Jesus over a cliff, and Jesus walked away (Lk 4:30). Humble yourself and give the Lord the opportunity to exalt you (Mt 23:12).