(Jeremiah, xxiii.6)

My God, how perfect are Thy ways!
But mine polluted are;
Sin twines itself about my praise,
And slides into my prayer.

When I would speak what Thou hast done
To save me from my sin,
I cannot make Thy mercies known,
But self-applause creeps in.

Divine desire, that holy flame
Thy grace creates in me;
Alas! impatience is its name,
When it returns to Thee.

This heart, a fountain of vile thoughts.
How does it overflow,
While self upon the surface floats,
Still bubbling from below.

Let others in the gaudy dress
Of fancied merit shine;
The Lord shall be my righteousness,
The Lord forever mine.

William Cowper

http://www.poemhunter.com/poem/jehovah-our-righteousness/