The reply (of disputed authenticity, but plausible and an important part of national legends nonetheless):

You Turkish Satan, brother and comrade of the damned devil and secretary to Lucifer himself! What the hell kind of knight are you? The devil s[hit]s and you and your army swallow [it]. You aren’t fit to have the sons of Christians under you; we aren’t afraid of your army, and we’ll fight you on land and sea.

You Babylonian busboy, Macedonian mechanic, Jerusalem beerbrewer, Alexandrian goatskinner, swineherd of Upper and Lower Egypt, Armenian pig, Tatar goat, Kamenets hangman, Podolian thief, grandson of the Evil Serpent himself, and buffoon of all the world and the netherworld, fool of our God, swine’s snout, mare’s a[ssho]le, butcher’s dog, unbaptized brow, may the devil steam your a[s]s!

That’s how the cossacks answer you, you nasty glob of spit! You’re unfit to rule true Christians. We don’t know the date because we don’t have a calendar, the moon [=month] is in the sky, and the year is in a book, and the day is the same with us as with you, so go kiss our b[ut]t!