Rav Moshe was the second son of Rav Yisroel of Kozhnitz.
He was the son-in-law of Yehuda Leib of Anipoli, the author of Ohr HaGanuz. In his second marriage, he was the son-in-law of Rav Elazar of Lizhensk.
His elder brother Rav Mordechai was sickly and died in his father’s lifetime, and Rav Moshe too suffered weakness and ill health. His survival is attributed to his father’s tefillos along with the tefillos of Rav Levi Yitzchok of Berditchev.
He hid his greatness so effectively that after his father’s passing many chassidim were unsure of whether he should lead as successor. Finally, the Chozeh of Lublin appointed him as rebbe saying “Vayehi binsoa haarov v’yomer Moshe –And it was when the ark began to travel, Moshe spoke...” And so it was.
They say his sister Margalis and brother-in-law Aviezra Zelig of Grenitz once entered his room to convince him to give up his position. But they suddenly abandoned the idea and left in suddenly. “Let us go, I saw my father himself-- may his memory be a blessing-- sitting right there beside him!” his sister remarked.
Rav Moshe donned the mantle of leadership in תקע"ה.
The Apta Rav, Rav Avrohom Yehsua Heschel, author of Ohev Yisroel, declared: “His father, Rav Yisroel, was the aspect of Dovid Hamelech, and so is his son!” (Sifran Shel Tzaddikim) Another time he remarked that: “They do not open up the gates in heaven until Rav Moshe of Kozhnitz begins to daven!”
The Rebbe of Parisov sat at a seuda commemorating the hillula of the Be’er Moshe of Kozhnitz. He remarked that his uncle, Rav Yerachmiel of Peshischa, used to say that Rav Moshe’s greatness would remain unknown until the coming of Mashiach. He said further, that even after Mashiach arrived, we still would not know the true greatness of Rav Moshe of Kozhnitz! (Sifran Shel Tzaddikim)
He left behind several seforim: Be’er Moshe on the Torah which was printed around thirty years after his passing, Va’Yachel Moshe on Tehillim, Mateh Moshe on Haggadah Shel Pesach, Tefillah l’Moshe on Sukkos, Da’as Moshe, Binas Moshe on the Torah, and Koheles Moshe on the Torah.
Rav Moshe passed away on the 12th of Elul 1828 (תקפ"ח), and was laid to rest in Kozhnitz. His youngest son, Rav Elazar, succeeded him.
