'Letters' in the Bible

And I said to the king, If it please the king, let letters be given me to the governors beyond the river, that they may set me forward till I come into Judah;

And I came to the governors beyond the river, and gave them the king's letters. Now the king had sent captains of a force and horsemen with me.

Moreover in those days the nobles of Judah sent many letters to Tobijah, and those of Tobijah came to them.

Also they spoke of his good deeds before me, and reported my words to him. And Tobijah sent letters to put me in fear.