But be not ye called Rabbi (umei de mh klhqhte Rabbei). An apparent aside to the disciples. Note the emphatic position of umei. Some even regard verses John 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.