really and truly

really and truly

Genuinely, undoubtedly. This redundancy (really and truly mean the same thing, but the repetition makes for emphasis) dates from the eighteenth century. The OED holds it is a North American children’s locution, but nearly all of its citations, ranging from Henry Fielding (1742) to the present, are from adult books. Thomas Macaulay used it in his The History of England (1849), “The king is really and truly a Catholic.”
See also: and, really, truly
References in classic literature ?
"I guess you'll think it's really and truly," prophesied Nancy, exultingly, nodding her head to Pollyanna over the armful of dresses she had taken from the closet.