Irony

Saying one thing while meaning another, often the opposite. The true sense is left to the reader or listener.

In Inferno

Cagnazzo, at this speech, raised his snout and, shaking his head, said: listen to the malice he thought up to throw himself down there! And he, who had plenty of snares, replied: I am too malicious, when I seek the greatest sorrow of my own.

By declaring himself "too malicious", the Navarrese admits his cleverness at the very moment he uses it. The apparent self-accusation is a way out: he says the opposite of what he wants, and the confession serves his plan.

Cantos XVIII to XXII: The First Five Ditches, Cagnazzo, one of the devils, and the Navarrese, who proposes whistling to call other damned souls

but now extend your hand here; open my eyes. And I did not open them; and it was courtesy to be a villain to him.

Cantos XXXI to XXXIV: The Ice and Lucifer, Dante, denying Fra Alberigo what he had promised, in Ptolomea