to be sure

They call themselves gentlemen, I warrant you; but, as my first husband used to say, they should remember it is we that pay them. And to be sure it is very hard upon us to be obliged to pay them, and to keep 'um too, as we publicans are.

1749, Henry Fielding, The History of Tom Jones, a Foundling, volume (please specify |volume=I to VI), London: A[ndrew] Millar, […], →OCLC

John spent the morning looking at these things; and, when it was mid-day, a bell rung, and his servant said, "Will you dine alone, sir, or with the large company?" - "With the large company, to be sure." replied John.

1828, Thomas Keightley, The Fairy Mythology, volume I, London: William Harrison Ainsworth, page 295

“Good-night, Captain, many thanks. You did it uncommonly well; how kindly the old un swallowed the spice-nut, to be sure; and it is only one of many others he has swallowed within these two days. I am afraid in about another four-and-twenty hours they will begin to disagree with him unless his stomach is a very strong one.”

1862, Wyndham Smith, Once a Week

But to be sure baby was as good as gold, a perfect little dote in his new fancy bib.

1922 February 2, James Joyce, “[Episode 13]”, in Ulysses, Paris: Shakespeare and Company […], →OCLC