'Letters' in the Bible

Hezekiah sent word to all Israel and to Judah and also wrote letters to Ephraim and Manasseh to come to the house of the Lord at Jerusalem to celebrate the Passover Feast to the Lord God of Israel.

So the runners went throughout Israel and Judah with the letters from the hand of the king and his officials, in accordance with the command of the king, saying, “O sons (descendants) of Israel, return to the Lord God of Abraham, Isaac, and Israel (Jacob), so that He will return to those of you who escaped and are left from the hand (power) of the kings of Assyria.

The Assyrian king also wrote letters insulting and taunting the Lord God of Israel, and speaking against Him, saying, “As the gods of the nations of other lands have not rescued their people from my hand, so the God of Hezekiah will not rescue His people from my hand.”