Other roles he became associated with were Zaccharia in Nabucco , Rocco in Fidelio , Osmin in The Abduction from the Seraglio , Pimen in Boris Godunov , Timur in Turandot , Ramphis in Aida , Pistol in Falstaff , Kekal in The Bartered Bride , Baron Ochs in Der Rosenkavalier ,