'Letters' in the Bible

Ahab had seventy sons living in Samaria. So Jehu wrote letters and sent them to Samaria to the leading officials of Jezreel and to the guardians of Ahab's dynasty. This is what the letters said,

At that time Merodach-Baladan son of Baladan, king of Babylon, sent letters and a gift to Hezekiah, for he had heard that Hezekiah was ill.