I lately heard this attributed to Lord Coke, responding to King James I, who (so it seems) wanted Coke to knock it off, else he (James) would knock it off.
Charming and plausible--Coke was, after all, a man with a sharp tongue and evident physical courage. But my friend Carlton, who is much better at Coke than I am, says it is a new one on him.
And so off to Google, which availeth not. And so? Is it out there but unGoogled (can anything be unGoogled?)?--in Catherine Drinker Bowen's charming but not particularly reliable biography, perhaps (but isn't that in Google books?--I haven't checked)? Am I misquoting? Or--
I suppose it could be Tom Lehrer (snark).