Turandot premiered at La Scala in Milan on 25 April 1926, almost a year and a half after Puccini’s death. Puccini’s friend Arturo Toscanini, who had worked on the score with the composer during the last months of Puccini’s life, conducted the premiere. As is widely recorded, when the opera reached the last note written by Puccini, Toscanini ended the performance. What he said at the time has been variously reported, from the poetic “Here death triumphed over art” to the poigniant “For me, the work ends here.” An eyewitness quoted in a recent biography puts it somewhere between the two: “Here ends the opera, because at this point the maestro was dead.”
FROM http://www.theopera101.com/operas/turandot/