Rabbi Yitzchak Mattisyahu Weinberg was a prominent Slonimer Hasid from New York, deeply involved in traditional Jewish communal life. He was the grandson of Rabbi Avraham Weinberg, the first Slonimer Rebbe and author of Yesod HaAvodah, and the son of Rabbi Noah Weinberg of Slonim and Tiberias, whom the first Rebbe had sent to Palestine in the late 19th century to establish a Torah community. Yitzchak Mattisyahu was married three times and raised a family steeped in Orthodox Jewish values, contributing to the continuity of the Slonim dynasty in America. He is best known as the father of Rabbi Yisrael Noah Weinberg (1930-2009), the influential founder of Aish HaTorah, an organization dedicated to outreach and education for unaffiliated Jews. Yitzchak also had other notable sons, including Rabbi Yaakov Weinberg, who became a respected rosh yeshiva at Yeshivas Ner Yisroel in Baltimore. Through his children, Yitzchak Mattisyahu extended the legacy of Slonimer Hasidism and Torah scholarship across generations. His life exemplified devotion to Hasidic traditions and family, instilling rigorous Jewish observance in his household. His wife Hinda (Noah's mother) was a direct descendant of Jacob ben Jacob Moses of Lissa. While specific details of his personal activities are limited, his role as a patriarch in a rabbinic family underscores his influence within Orthodox Jewish circles in mid-20th century America.