From Inside the Vatican:

In a remarkable historical find, testimony has emerged revealing that, in 1941, Pope Pius XII received a German Jewish visitor at the Vatican who was seeking help for certain Jews who were being held in an Italian internment camp. After welcoming the young man and promising him help, Pius told him not once but twice–in emotional language, in front of a large group that included German soldiers–"Be proud to be a Jew!"

The amazing testimony, written as a first-hand account by an anonymous Jewish author in wartime Palestine, originally appeared on April 28, 1944 in The Palestine Post (now, The Jerusalem Post), the most influential Jewish publication in the world at that time.

According to longtime Inside the Vatican contributor William Doino, who discovered the testimony in an archive, maintained by Tel Aviv University, "the testimony has apparently been forgotten, because, as far as I know, no leading Holocaust authority or biographer of Pius XII has ever cited it."