For mercies, countless as the sands, 
Which daily I receive 
From Jesus, my Redeemer's hands, 
My soul what canst thou give?  
 
Alas! from such a heart as mine, 
What can I bring him forth? 
My best is stained and dyed with sin, 
My all is nothing worth.  
 
Yet this acknowledgment I'll make 
For all he has bestowed; 
Salvation's sacred cup I'll take 
And call upon my God.  
 
The best returns for one like me, 
So wretched and so poor; 
Is from his gifts to draw a plea, 
And ask him still for more.  
 
I cannot serve him as I ought, 
No works have I to boast; 
Yet would I glory in the thought 
That I shall owe him most.
John Newton
http://www.poemhunter.com/poem/what-shall-i-render/