Unwarrantably

1662, Richard Baxter, A Saint or a Brute, London: Francis Tyton & Nevil Simmons, Chapter 4, p. , Holiness maketh men meek and patient, and teacheth subjects not to make too great a matter of any injury that is done them; nor to censure unwarrantably the actions of their superiours […]

1937, H. G. Wells, Star Begotten, Middletown CT: Wesleyan University Press, 2006, Chapter 8, 5, p. 118, There is this secondary world which has worked its way into language everywhere, a sort of fold in the membrane that has established itself in a thousand metaphors, got itself most unwarrantably taken for granted by nearly everybody.

Applied to any other creature than the Leviathan—to an ant or a flea—such portly terms might justly be deemed unwarrantably grandiloquent.

In the following year, however, a contract for the remainder of the line was concluded, and the directors issued a most unwarrantably optimistic report on the prospects of their undertaking.