αὐχεῖν

From LSJ

δὶς ἐξαμαρτεῖν ταὐτὸν οὐκ ἀνδρὸς σοφοῦ → a wise man should not keep making the same mistake, a wise man should not repeat the same mistake, doing twice the same mistake is not a wise man's doing, making the same mistake twice does not befit the wise, making the same mistake twice does not belong to a man who is wise, making the same mistake twice does not belong to a wise man, the wise man does not make the same mistake twice, to commit the same sin twice is not a sign of a wise man, it is unwise to err twice

Source

Greek > English (Woodhouse Verbs Reversed)

(see also αὐχέω): assert, boast, declare, assert confidently, be confident

Lexicon Thucydideum

gloriari, to boast, 2.39.3.