I’ve never heard of the girl scout oath. I just checked some old gs manuals and none of them mention an oath. There is a gs promise and as of the 1975 edition of the Cadette manual, it contained service to God, my country and mankind.
If I remember right: On my honor, I will try, to do my duty, to God and my country. Something something every day, and to obey the girl scout laws. (girl scout in 1958-63.