'Letter' in the Bible

And I have written this very letter to you, that coming I may not have grief from those from whom I ought to have joy; trusting in you all that my joy is that of you all.

Ye are our letter, written in our hearts, known and read of all men,

who has also made us competent, as ministers of the new covenant; not of letter, but of spirit. For the letter kills, but the Spirit quickens.

For if also I grieved you in the letter, I do not regret it, if even I have regretted it; for I see that that letter, if even it were only for a time, grieved you.