On June 29, 1972 at a Mass for the Feast of Saints Peter and Paul and on the ninth anniversary of his coronation as Pope, Paul VI delivered a homily that included saying that through some opening the smoke of Satan has entered the Temple of God. Or so it can be translated from the "da qualche fessura sia entrato il fumo di Satana nel tempio di Dio" of the Italian text at the Vatican website. The full text had not been translated into English or any other language there. Fr. Stephanos Pedrano provided his translation to Jimmy Akin.
The phrase is also referenced at the Vatican website in a homily by Cardinal Bertone on September 6, 2008, the 30th anniversary of Pope Paul's death, and in this interview of Cardinal Battista Re by Mario Ponzi in L'Osservatore Romano, November 4, 2009, both also in Italian.