Which preposition to use with mumblers

of Occurrences 1%

But in the abbey at that time was a cloister-monk named Friar John of the Trenchermen, young, gallant, frisky, lusty, nimble, quick, active, bold, resolute, tall, wide-mouthed, and long-nosed; a fine mumbler of matins, a fair runner through masses, and a great scourer of vigilsto put it short, a true monk, if ever there was one since the monking world monked a monkery.

Which preposition to use with  mumblers