My question was if there is a source for the actual words, not what is was based on.
I'm puzzled by the actual words. They seem completely inconsistent with the actual order of the events (which is why I'm asking about them).
Case in point - the first lyrics. "Nichnas Lemakom Shenichnas, Amad Lemakom She'amad." Those are words describing the Kohen Gadol going back into the Kodesh Hakedashim. But a few words later is "Pashat Bigdai hachol, lavesh bidai lavan," which happened earlier. A few words later, he says "Ana hashem Kaper... ani ubaisi". That happened before the Kohen Gadol went into the Kodesh Hakedashim for the first time.
That being the case, I'm wondering if this is just a loose song with a bunch of random phrases, or if there is something here I'm missing.