A.T. Robertson Commentary Matthew 23:8

"But be not ye called Rabbi: for one is your teacher, and all ye are brethren." — Matthew 23:8 (ASV)

But be not ye called Rabbi (υμεις δε μη κληθητε Ραββε). An apparent aside to the disciples. Note the emphatic position of υμεις. Some even regard verses 8-10 as a later addition and not part of this address to the Pharisees, but the apostles were present. Euthymius Zigabenus says: "Do not seek to be called (ingressive aorist subjunctive), if others call you this it will not be your fault." This is not far from the Master's meaning. Rabbi means "my great one," "my Master," apparently a comparatively new title in Christ's time.