Head of the Kaliv Hasidic dynasty and Holocaust remembrance advocate Rabbi Menachem Mendel Taub passed away on Sunday at his home in Jerusalem at the age of 96.

Thousands attended the funeral of the haredi religious leader on Sunday afternoon.

Born in Transylvania in 1923, Rabbi Taub was taken to the Auschwitz concentration camp in 1944 and subjected to chemical experiments by Dr. Josef Mangele which left him unable to grow a beard or father children.

Though his brothers and much of his community were killed by the Nazis, Rabbi Taub’s wife Chana Sarah survived, and the two were reunited in Sweden after the Holocaust. She passed away in 2010, and Rabbi Taub remarried two years later, to 55-year-old Sheindel Malnik of Bnei Brak.

As a Holocaust survivor, Rabbi Taub was an ardent advocate for Holocaust remembrance and education, and urged the public to focus not just on the physical resistance to the Nazis during the war, but rather on the spiritual resistance of pious Jews who risked and gave their lives to keep and preserve Jewish heritage and Torah commandments.

Though the haredi world generally eschews nationalist holidays such as Holocaust Remembrance Day and Israel’s Independence Day, Rabbi Taub would frequently give interviews to Israeli news outlets ahead of Holocaust Remembrance Day, and once attempted to erect a Holocaust museum commemorating the murder of Europe’s Jews from a haredi perspective.

“Why do we give more importance to the physical fighters?” Rabbi Taub said in a 2000 New York Times article. “How about the rabbis and yeshiva students who clung to the religious commandments until the end? Did they not defend the soul of the Jewish people? Are they not as important to Israel today as F-16s and A-bombs?”

Taub was known for reciting the Shema prayer in public at ceremonies honoring Holocaust victims, a practice he vowed to take upon himself after screaming the prayer while SS guards rounded him and others up to burn them. He vowing to recite the prayer with living Jews if God would spare his life.

“I saw people being put into the fire,” Rabbi Taub told Makor Rishon newspaper in 2001. “One of them yelled out before he was killed: ‘If one of you survives, do not forget to say Kaddish for me!’ Then, when the horrible Holocaust occurred, I started to think about perpetuating the memory of the holy victims. Who will say Kaddish? Who will tell the story? Who will say ‘Shema Yisrael?’”

Israeli Prime Minister Benjamin Netanyahu expressed his “deep sorrow” over Rabbi Taub’s death, saying the rabbi had “survived the horrors of the Holocaust and dedicated himself to rebuilding the world of Torah in the State of Israel and among the Jewish Diaspora. At the same time, he was tirelessly engaged in enshrining the memory of the Holocaust, especially the triumph of the impressive spirit in the ghettos and camps. The passing of the Admor of Kaliv close to Holocaust Martyrs’ and Heroes’ Remembrance Day strengthens our eternal commitment—to remember and not forget. May his memory be blessed.”

Israeli President Reuven Rivlin said, “I received with deep sadness the news of the passing of the Admor of Kaliv, the ‘Holocaust Admor’ who suffered horribly as a prisoner at Auschwitz and dedicated his life to the memory of the victims, inspired by true love of Israel.”

“The Admor gave voice to the spiritual heroism of Jews during the Holocaust and did all he could to honor the memory of its victims. His work has particular resonance at present as we redouble our commitment to remember and never to forget. We send our condolences to his family and many pupils. May his memory be a blessing.”

“The people of Israel bow their heads at the passing of Rabbi Menachem Mendel Taub, the Admor of Kaliv, an ember saved from the fires [of Auschwitz] who dedicated his life, Torah and Hasidism to commemorating the Holocaust,” Knesset member Gila Gamliel (Likud) said. “We lost today a great leader and a great educator, who was an example to us all, heroically and personally and nationally, who after his family was lost in the Holocaust, immigrated to Israel, arose and established holy Torah projects and memorials. How sad to lose those who cannot be replaced. May his memory be blessed.”