[I am unwilling to accept the office of bishop. ] A very general notion prevails that every bishop at consecration uses these words. Mr. Christian, in his notes to Blackstone, says, “The origin of these words and of this vulgar notion I have not been able to discover; the bishops certainly give no such refusal at present, and I am inclined to think they never did at any time in this country.” When the see of Bath and Wells was offered to Beveridge, he certainly exclaimed, “Nolo episcopari, ” but it was the private expression of his own heart, and not a form of words, in his case. Chamberlayne says in former times the person about to be elected bishop modestly refused the office twice, and if he did so a third time his refusal was accepted.
(Present State of England.)
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894