In his commentary on the Mishnah (tractate Sanhedrin, chapter 10), Maimonides formulates his “13 principles of faith”. They summarized what he viewed as the required beliefs of Judaism:
Maimonides compiled the principles from various Talmudic sources. These principles were controversial when first proposed, evoking criticism by Rabbi Hasdai Crescas and Rabbi Joseph Albo, and were effectively ignored by much of the Jewish community for the next few centuries. (“Dogma in Medieval Jewish Thought,” Menachem Kellner). However, these principles have become widely held; today, Orthodox Judaism holds these beliefs to be obligatory. Two poetic restatements of these principles (Ani Ma’amin and Yigdal) eventually became canonized in the “Siddur” (Jewish prayer book).