Apparently we are not sure just exactly what he said....
In Part Two of the play Beckett is confronted and murdered by Four Knights, acting at the behest, explicit or otherwise, of Henry. Beckett had further antagonized Henry, upon his return, by opposing the coronation of Henry's son. This prompted the King to his infamous utterance : "Who will rid me of this turbulent priest?"
On December 29, 1170, four knights of his court assassinated Beckett inside the Canterbury cathedral, turning an already heinous act into a cause celebre throughout Christendom. Eliot uses this section of the play to explore the possibility that Beckett was actually wrong in his argument with Henry.
http://www.brothersjudd.com/webpage/pla ... ecathedral
http://www.amazon.com/exec/obidos/ASIN/ ... 87-4571038
In 1170 Thomas returned to England. Meanwhile, back in France, the most ardent opponent of Thomas, who was Archbishop Roger of York had the ear of the King. Archbishop Roger, who, as Archbishop of York, would have been number two in the hierarchy of the Church in England, suggested to Henry that, 'while Thomas lives, you will have neither quiet times nor a tranquil kingdom'. This threw Henry into one of his rages and he was supposed to have exclaimed one of the following:
"Who will rid me of this meddlesome priest"
"Who will rid me of this low-born priest"
or, "Who will rid me of this turbulent priest"
Whichever words he used, they were overheard by four of his knights. The knights were; Richard Brito, Hugh de Moreville, Reginald FitzUrse, and William de Tracy.