On the day following Simchat Torah, the most joyous celebration in the Jewish calendar, the world heard the devastating news that one of Jewry’s greatest 20th-century talmidei chachamim, who combined his exceptional Torah scholarship with a stellar career in microbiology, had passed from this world.

Born in 1926 on the Lower East Side, Rabbi Dr. Moshe Dovid Tendler zt”l was niftar at the age of 95 on September 28. His levayah on Thursday, September 30, filled to capacity the Community Synagogue of Monsey where he served as its devoted rav since 1967. It was also broadcast live to grieving followers throughout the world. In addition to serving as a Yeshiva University rosh yeshiva who taught Talmud at the highest levels, he also held an endowed chair as a Yeshiva University professor of microbiology and Jewish medical ethics, and as chair of the biology department.

Rabbi Tendler, a son-in-law of the great 20th-century posek Rabbi Moshe Feinstein zt”l, was also a world-renowned posek in his area of expertise, that of the halacha regarding organ donation, brain death, life-or-death medical emergencies of all kinds, as well as even more intricate or esoteric topics in halachah, such as the permissibility of molecular genetics in artificial insemination.

The three-hour levayah included tributes by his eight sons and sons-in-law, who spoke of the seismic accomplishments of Rav Tendler in the fields of Torah scholarship and modern Jewish medical ethics, of which he was considered the founding father. Poignantly, they also shared their memories of the warmth that he exuded toward his children and grandchildren, trying until late in life not to ever miss attending milestone occasions in their lives. Even his petirah on Shemini Atzeret was a consideration for his family to have completed all the Yomim Tovim and even allow travel time for the three families living in Israel to arrive in time to participate in the levayah.

In succession, the sons and sons-in-law pointed out Rav Tendler’s insistence upon understanding halacha from the context of metzius, that which is the reality of the day, but never compromising in its observance. His goal was to teach emet (truth), which was not always the popular view.

They spoke of the endless hours he spent in limud Torah with his family and his congregation, especially during Shabbos and Yom Tov. They praised the extraordinary efforts he put into answering any shailot brought to him by studying the issue thoroughly and then following up with the implementation. He was known to check up on his congregants unannounced during Pesach to make certain that their chametz was properly disposed of.

He was a man of strength both physically and in his convictions and did not shy away from controversy as long as its goal was l’shem shamayim (for the sake of heaven). He confidently accompanied a son-in-law onto Har Habayit, fully aware of its controversial implications. Throughout his life he sought to discover what Hashem wanted from him and to comply through his life’s work.   

Rav Reuven Feinstein, brother-in-law of Rav Tendler, recalled the close relationship Rav Tendler had with his illustrious father-in-law Rav Moshe. He recalled the kavod and derech eretz that Rav Tendler showed to Rav Moshe during their often intense discussions regarding the halachot of medical ethics. In one of the most controversial halachic discussions regarding organ transplants from a dying patient, Rav Tendler studied the biological process of death with Rav Moshe, which resulted in the ruling that brain death was the marker needed for permission to harvest organs in order to save lives.

Rav Tendler was born on the Lower East Side of Manhattan to Rabbi Isaac Tendler, head of the Rabbi Jacob Joseph Yeshiva, and mother Bella, an attorney. He studied at the Jacob Joseph Yeshiva and married Rav Moshe’s daughter Shifra, whom he met at a local library where she posed a question relating to chemistry to the young Tendler. He earned his undergraduate degree at New York University, followed by his Semicha at Yeshiva University in 1949. He went on to earn a doctorate in microbiology from Columbia University in 1957. During his 80 years of affiliation with Yeshiva University as a student, rebbe, and biology instructor, he taught hundreds of students who went on to become doctors and rabbis.

Rabbi Hershel Schachter shlit”a also spoke at the levayah, remembering Rav Tendler as his rebbe from the age of 13 at MTA. He recalls how Rav Tendler would often quote Rav Soloveichik and would always bring contemporary issues into the classroom. “He gave his heart and soul to the yeshiva and was my last rebbe to pass away. Hopefully, his high level of learning will be perpetuated.”

Yeshiva University President Rabbi Dr. Ari Berman, who spoke following Rav Schachter, expressed that in representing everything that YU stands for, Rav Tendler actually removed the “vav” that connects Torah U’Madda. “Rav Tendler, who served as the Rabbi Isaac and Bella Tendler Professor of Jewish Medical Ethics and a Professor of Biology at YU, was the archetype of Adam I and Adam II as he combined the scientist with the Man of Faith. The world of Rav Tendler was not bifurcated but whole. His goal was to live an integrated life, to be one cohesive narrative as an eved Hashem. He wove a unified story as a teacher of Talmud b’iyun on the highest level while implementing biology with sophistication. His research team came very close to discovering a cure for cancer. He was constantly invited to address high-level national and international medical conferences, bringing honor to YU and the entire Jewish community. His 80-year affiliation with YU, beginning as a high school student to becoming a top rebbe and professor, enabled us to prepare qualified future leaders. His collaboration with Rav Moshe on teshuvot regarding medicine and halacha guides Jewish practice to this day throughout the world.”

Rav Tendler leaves a legacy of numerous publications on issues including euthanasia, infertility, end-of-life, organ donation and brit milah. He was a strong advocate of the use of a tube when performing metzitzah b’peh, suction of blood during a circumcision. He headed the RCA panel on stem cell research and served as the posek and past president of the Association of Orthodox Jewish Scientists.

Rav Tendler is survived by five sons and three daughters, and many beloved grandchildren and great-grandchildren. His beloved wife, Shifra Feinstein Tendler, passed away in 2007.