'Letters' in the Bible

Then Hezekiah sent word to all Israel and Judah, and sent letters to Ephraim and Manasseh, requesting them to come to the house of the Lord at Jerusalem, to keep the Passover to the Lord, the God of Israel.

So runners went with letters from the king and his chiefs through all Israel and Judah, by the order of the king, saying, O children of Israel, come back again to the Lord, the God of Abraham, Isaac, and Israel, so that he may come again to that small band of you which has been kept safe out of the hands of the kings of Assyria.

And he sent letters, in addition, to put shame on the Lord, the God of Israel, and to say evil against him, saying, As the gods of the nations of other lands have not been able to keep their people safe from my hands, no more will the God of Hezekiah keep his people safe from my hands.