ἐθέλω περὶ τῆς κεφαλῆς περιδόσθαι

From LSJ

γνοίης ὅσσον ὄνων κρέσσονες ἡμίονοι → you know how much better are donkeys from mules

Source

English > Greek (Woodhouse Quotes Reversed)

I am willing to wager my head