Photo Credit: Rabbi Nadel
The author with Rav Tendler on Har HaBayis.

The Talmud (Mo’ed Katan 25b) relates that following the death of Rabba and Rav Yosef, the bridges over the Euphrates collapsed into one another; and following the death of Abaye and Rava, the bridges over the Tigris collapsed into one another. These great Sages were “bridges” – ba’alei mesorah – connecting one generation to the next. And their deaths marked the end of an era.

Moreinu HaRav Moshe Dovid Tendler, zt”l, was a living link in the chain of tradition. He connected us to the gedolim of the previous generations, all the way back to Sinai. And his death too marks the end of an era.


Rav Tendler was many things: A posek and a professor. A rosh yeshiva and a scientist. A world-class talmid chacham with a Ph.D. in microbiology. A communal leader and synagogue rabbi. But to me, he was a rebbe.

His shiur was unlike any other in the yeshiva. Rav Tendler wouldn’t get lost in abstractions, pilpulim, or lomdus. Instead, his shiur focused on the practical application of halacha. The sugya would come to life – pirouetting off the page of the Gemara – as Rav Tendler would share real questions and cases he was involved in, drawing on years of experience as a posek. We would often look together at the teshuvot of his beloved shver, HaGaon Rav Moshe Feinstein, zt”l, with Rav Tendler providing fascinating footnotes and important background information to the teshuvah.

Rav Tendler defined Torah l’shmah – the study of Torah for its own sake – as “l’shem hora’ah,” for the sake of being able to rule; to render p’sak halacha. He would invoke Kiddushin 30a: “The words of Torah should be sharp in your mouth, so should someone ask you a question you will not stammer [but] answer him immediately.” He was critical of those who study in yeshiva or kollel for many years, but when asked how to make a cup of tea on Shabbos, “don’t want to pasken.”

It was not uncommon for me to be sitting with him in his office at Yeshiva University, or at his home in Monsey, NY, when he would receive a phone call, usually from across the globe, on some serious matter. And it was also not uncommon for him to gesture to me to pick up the phone and listen in on the conversation, so I could hear how he navigated the complex question.

He wanted his talmidim to be competent and confident in answering a shayla.

He was also the address when the answer was unclear, or the question too great for a newly-minted rabbi. We knew we could turn to him and he would guide us, always generous with his time.


Talmidim Were Like Family

Rav Tendler treated us like his own children, and our children like his grandchildren. Our s’machot were his s’machot, and our successes were his successes. He was deeply invested in his talmidim, and was so proud of their accomplishments. Together with his late Rebbetzin Shifra, a”h, he would open up his home to us for Shabbat, Yom Tov, and Chanukah.

For decades, Rav Tendler served with distinction as a rosh yeshiva at Yeshiva University’s Rabbi Isaac Elchanan Theological Seminary and professor of Biology and Jewish Medical Ethics at Yeshiva College. He entered the yeshiva at the age of 13 in 1939, and in his own words, “never left.” YU’s motto of Torah U’Madda was his personal mantra. He brought science into the beit midrash and Torah into the laboratory. Sophisticated sugyot were illuminated by scientific material, and his biology classes were peppered with statements of Chazal.

As a preeminent posek and pioneer in the field of medical halacha, Rav Tendler ruled on the most difficult and delicate areas of halacha: Complicated questions of pikuach nefesh, end-of-life issues, organ donation, agunot, abortion, and reproductive medicine. He answered them all with surgical precision, great finesse, and a great sense of responsibility.

Rav Tendler also developed a cancer drug he named Refuin. A Time magazine article in 1963 described how “the discovery made by Dr. Moses D. Tendler… took on an aura of romance because he spends only part of his time in the laboratory, the rest in his study as a Talmudic scholar.”

His saintly father-in-law, Rav Moshe, turned to his beloved son-in-law with questions of medical procedures or innovations in science and technology. Rav Tendler is quoted in dozens of teshuvot in the Igrot Moshe, providing the necessary information needed.

Rav Tendler saw no conflict between Torah and science. For him, they lived together in perfect harmony. He was equally at home quoting Galen as he was quoting the Rambam.


A Long Lost World

Born in 1926, he would often say that he was born in a “small shtetl in Europe, known as the Lower East Side of Manhattan.”

“Hitler killed more than six million Jews, he destroyed a culture that you kids don’t even know about,” he would remark. And in his shiur we were transported to a long lost world where a man dressed in tatters knew every Tosafot by heart and could be asked any question on any page of the Talmud.

Rav Tendler would share stories of how as a child he would accompany his maternal grandfather, Rav Shalom Baumrind, known as the Boyaner Mohel, to the fish market for kapporos, where he would buy a live carp and place a piece of bread soaked in schnapps in its mouth. He shared how the same grandfather would take him to the Boyaner Rebbe’s tish, which he remembered as being regal and majestic, but to his grandfather’s chagrin, still refused to take the Rebbe’s shi’rayim. He recalled how his grandmother used to cut the bottoms of carrots first, as it’s not nice to chop off the head.

He connected us to the gedolim of previous generations. As a bachur, he would read the Gemara for an elderly, blind Rav Yosef Eliyahu Henkin, zt”l, who sat on wooden orange crates so as not to take money from the yeshiva for furniture. He shared stories of his father, Rav Yitzchak Isaac Tendler, zt”l, who served as a rosh yeshiva at RJJ and the rav of the Kaminetzer Shul for decades, and his father’s rebbe, Rav Boruch Ber Leibowitz, zt”l. Often, while relating a story about his beloved shver, Rav Tendler would have to hold back the tears.

For Rav Tendler, sharing these stories and anecdotes was not bittul Torah. “Even the mundane conversations of talmidei chachamim requires study” (Avoda Zara 19b), he said. He was connecting us with the mesorah. He taught his students more than just a blatt Gemara; he gave us a glimpse into greatness.

Rav Tendler was a towering intellectual giant, but at the same time very down to earth and easily approachable. Famous for his wry sense of humor, he possessed a sharp wit and biting sarcasm. Once, when asked by a student if a certain decadent dessert made with dairy equipment can be eaten after meat, he scratched his beard and wondered aloud if it should be eaten at all, given how unhealthy it is.

As a posek he could be unyielding, uncompromising, and unapologetic. He lived the Torah’s charge to the dayan: “You shall not tremble before any man” (Devarim 1:17). Whether it was brain death, metzitza b’peh, or ascending the Temple Mount, he was unafraid to take a controversial position, even at great personal cost. He strove for truth, often quoting the Maharshal’s comment that any distortion of the Torah is yehareg ve’al ya’avor (See Yam Shel Shlomo, Bava Kamma 4:9) or Rav Soloveitchik’s comparison of a posek who errs to a false prophet.

His illustrious career spanned decades dedicated to Jewish communal life. As a rosh yeshiva and the rabbi of Community Synagogue of Monsey, he helped shape Orthodoxy in America in the 20th century. His books and dozens of scholarly articles on the intersection of halacha, science and medicine guided generations and will continue to guide generations to come. He was blessed with arichut yamim, and continued giving shiurim until his most recent illness made it too difficult. He drew strength from his great love for the Torah and his great love for his talmidim.

“From Moshe to Moshe, no one arose like Moshe.” Like Moshe Rabbeinu, Moshe ben Maimon, and Rav Moshe Feinstein, Rav Tendler taught Torah to generations, connecting them to our mesorah.

Yehi zichro baruch.


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Rabbi Shimshon HaKohen Nadel lives and teaches in Jerusalem.