Yahrtzeit of Avraham Ben Avraham, a righteous convert who was burned at the stake in 1749. He was known as Count Valentine Potocki, whose conversion was a source of embarrassment to the Roman Catholic Church and the Polish noble class from which he came. After converting, he disguised his identity and moved to Vilna, Lithuania, then the center of Jewish life. When his true identity was discovered, he was arrested, and after a long imprisonment and trial for heresy by an Inquisition court, he was burned alive in Vilna. Potocki was so well-respected that his ashes are buried in the same gravesite as the revered Jewish sage, the Vilna Gaon, and prior to the Holocaust, all the synagogues of Vilna commemorated his yahrtzeit.