I used
http://www.biblegateway.com/ to search the NIV, and NASB ('cause those are the two I use), and the KJV, and NKJV ('cause those are the ones most people are familiar with) and the phrase "God will sing" doesn't occur anywhere in any of those translations.
I don't know as much about Early Modern English as I once did but the phrase "But ye not worthy" doesn't look properly constructed to me. Thus I'm inclined to think that it was made up by someone who wants you to think that it's from the King James Bible.
I have a friend who is a linguist (and is employed as a Latin teacher). Next time I talk to her I'll see what she thinks.