Assurance

Here's a prayer titled "Assurance" from "The Valley of Vision: A collection of Puritan Prayers & Devotions" edited by Arthur Bennett (pages 92-93):

ALMIGHTY GOD,

I am loved with everlasting love,

   clothed in eternal righteousness,

      my peace flowing like a river,

      my comforts many and large,

      my joy and triumph unutterable,

      my soul lively with a knowledge of salvation,

      my sense of justification unclouded.

I have scarce anything to pray for;

Jesus smiles upon my soul as a ray of heaven

   and my supplications are swallowed up in praise.

How sweet is the glorious doctrine of election

   when based upon thy Word

   and wrought inwardly within the soul!

I bless thee that thou wilt keep the sinner

     thou hast loved,

   and hast engaged that he will not forsake thee,

   else I would never get to heaven.

I wrong the work of grace in my heart

   if I deny my new nature and my eternal life.

If Jesus were not my righteousness and redemption,

   I would sink into nethermost hell

   by my misdoings, shortcomings, unbelief, unlove;

If Jesus were not by the power of his Spirit

   my sanctification,

   there is no sin I should not commit.

O when shall I have his mind!

   when shall I be conformed to his image?

All the good things of life are less than nothing

   when compared with his love,

   and with one glimpse of thy electing favour.

All the treasures of a million worlds could not

   make me richer, happier, more contented,

   for his unsearchable riches are mine.

One moment of communion with him, one view

   of his grace,

   is ineffable, inestimable.

But O God, I could not long after thy presence

   if I did not know the sweetness of it;

And such I could not know except by thy Spirit

   in my heart, nor love thee at all unless thou didst

   elect me,

   call me,

   adopt me,

   save me.

I bless thee for the covenant of grace.