I woke up with that line going through my head the other day. It seemed to me that it was from either a ritual or a poem I had read in my youth (putting it at least 25 years ago). I Googled the crap out of it in any variation I could think of, and didn’t even get a nibble.

Then it occurred to me that I have a veritable ragtag army of eclectic scholars of bizarre and marginal texts at my disposal: my readers! If any among you cognoscenti of marginal esoterica knows what the hell this little didbit of trivia floating around in my noggin is, please tell me what it is, because it’s really gnawing at me. It is possible my memory has mangled it up, but as I remember it, the line is “…and I am an exceeding strong seething.”
Maybe I need to start wearing my tinfoil hat again so the CIA can’t plant messages in my mind.