Pope Francis I on Monday sent a letter to Rabbi Abraham Skorka, his longtime friend from Buenos Aires, in commemoration of International Holocaust Remembrance Day, in which he calls the Holocaust “a horror and a disgrace to humanity that must never be repeated,” Vatican Radio reported.

According to the papal news outlet, Francis’s letter was to be read out Monday evening at a concert in Rome in which 12 violins that survived the Holocaust will be played. One of the violins, the news outlet reported, “accompanied the deportees to the gas chambers of Auschwitz.” 

Il Papa wrote to Rabbi Skorka that attendees of the “Violins of Hope” concert will hear pieces by Barber, Vivaldi and Beethoven, but “behind the sound of music, the hearts of each of those present will be able to make out the silent sound of tears,” Vatican Radio reported.

Rabbi Abraham Skorka speaks during an interview at the Jewish Theological Seminary in New York on Wednesday October 30, 2013. (photo credit: AP/Tina Fineberg)

Rabbi Abraham Skorka speaks during an interview at the Jewish Theological Seminary in New York on Wednesday October 30, 2013. (photo credit: AP/Tina Fineberg)

Last week, Skorka said Francis intended to make public the Vatican archives about Pope Pius XII’s actions during the World War II.

“I believe that, yes, he will open the archives,” the Jewish Chronicle quoted Skorka saying. “The issue is a very sensitive one and we must continue analyzing it.”