'Letters' in the Bible

Now Hezekiah sent to all Israel and Judah and wrote letters also to Ephraim and Manasseh, that they should come to the house of the Lord at Jerusalem to celebrate the Passover to the Lord God of Israel.

The couriers went throughout all Israel and Judah with the letters from the hand of the king and his princes, even according to the command of the king, saying, “O sons of Israel, return to the Lord God of Abraham, Isaac and Israel, that He may return to those of you who escaped and are left from the hand of the kings of Assyria.

He also wrote letters to insult the Lord God of Israel, and to speak against Him, saying, “As the gods of the nations of the lands have not delivered their people from my hand, so the God of Hezekiah will not deliver His people from my hand.”