Hi, Mary - the song is a direct quote from the Bible, Ruth 1:16-17. What you have is close to the King James Version:

And Ruth said,
Intreat me not to leave thee, or to return from following after thee
For whither thou goest, I will go;
And where thou lodgest, I will lodge;
Thy people shall be my people, and thy God my God.

Where thou diest, will I die, and there will I be buried: the Lord do so to me, and more also, if ought but death part thee and me.

This is often used at weddings, in one form or another. Interestingly, this is Ruth's pledge of fidelity to her mother-in-law, Naomi. By this time, Naomi's husband and two sons have died, leaving Naomi with just two daughters-in-law. Orpah, the other daughter-in-law, went back to her home country and became a famous talk show host; but Ruth insisted on staying with Naomi - and we end up with one of the more colorful and poetic books of the Bible.
-Joe Offer-