Naaman was a general in Aram, but he had tzaraas (a skin condition that for simplicity's sake we'll translate as leprosy, even though it's not exactly the same). Naaman's wife had a Jewish servant girl, who suggested that Elisha might be able to cure him. Naaman approached the king of Aram, who wrote Naaman a letter of introduction to Yehoram, king of Israel. Naaman brought with him silver, gold and clothes.
When Yehoram got the letter asking him to have Naaman cured, he was worried that Aram was merely seeking a pretext to go to war. Elisha heard about Naaman and sent word to the king that he should sent Naaman to him so that he'll know there's a prophet in Israel.
Elisha instructed Naaman to bathe seven times in the Jordan and he would be healed. Naaman scoffed at this. "We have better rivers in Damascus and they haven't cured me!" Naaman's servant said to him, "If the prophet told you to do a difficult thing, wouldn't you have listened? This is so easy, it's at least worth a shot!" So Naaman bathed in the Jordan. Not only was he cured of his leprosy, his skin was completely rejuvenated, like a young boy's.
Naaman returned to Elisha and offered him the riches he had brought, but Elisha declined. Naaman pressed him to take a gift, but Elisha stood firm.
"Well, I'm asking YOU for a gift," said Naaman. "Please let me load my caravan with the earth of the Holy Land so that I can build an altar. From now on, I will only worship Hashem and no other god." (Naaman stipulated that, when the king of Aram would take him to worship his gods, he would have to let the king think he was doing so. Elisha told him not to worry about it; a Jew would not be permitted to do so, but it was okay for Naaman.)
Excerpted from The OU's Nach Yomi