Is it ensure, insure, or assure?
"make quick taps," 1610s, frequentative of pat (v.). Related: Pattered; pattering. As a noun in this sense from 1844.
"talk rapidly," c.1400, from pater "mumble prayers rapidly" (c.1300), shortened form of paternoster. Perhaps influenced by patter (v.1). The related noun is first recorded 1758, originally "cant language of thieves and beggars." Cf. Devil's paternoster (1520s) "a grumbling and mumbling to oneself."
PATTERING. The maundering or pert replies of servants; also talk or palaver in order to amuse one intended to be cheated. ["Dictionary of Buckish Slang, University Wit and Pickpocket Eloquence," London, 1811]