A.T. Robertson Commentary Matthew 20:22

"But Jesus answered and said, Ye know not what ye ask. Are ye able to drink the cup that I am about to drink? They say unto him, We are able." — Matthew 20:22 (ASV)

Ye know not what ye ask (ουκ οιδατε τ αιτεισθε). How often that is true. Αιτεισθε is indirect middle voice, "ask for yourselves," "a selfish request."

We are able (δυναμεθα). Amazing proof of their ignorance and self-confidence. Ambition had blinded their eyes. They had not caught the martyr spirit.