||The Rambam's count of the precepts with the commentary of the Ramban and R. Isaac de Leon.
In the enumeration of all the commandments of the Torah, which, according to tradition, numbered 613, great confusion existed before the time of Maimonides, since no principle of classification was established, and consequently the various systems conflicted in many respects. As a sort of introduction to his new code, Maimonides prefixed to it a work containing a dry list of all the commandments of the Torah. In the "Sefer ha-Mizvot" he systematized the commandments by deducing them from fourteen self-evident principles, enumerating the 613 commandments on this basis. This work was generally accepted, and formed the foundation of the majority of subsequent lists. It must be admitted, however, that Maimonides himself frequently deviated from his own rule and cited individual commandments which, according to his system, could not be regarded as precepts, a point to which attention was called as early as the time of Nahmanides.
After establishing the list of all the injunctions of the Torah in his "Sefer ha-Mizvot," Maimonides proceeded to write his great work, the "Mishneh Torah," on which he labored for ten successive years. In this book he planned a complete legal system which should give in a brief but clear form the final decision in the case of each law, so that, by the omission of long discussions and demonstrations, every regulation, law, and custom of religious life might be learned without any other manual. He named the work, therefore, the "Mishneh Torah," or the "Second Law," since it was only necessary to read first the written Torah and then this work in order to acquire the entire body of the so-called "oral law." The book contains all definitions of the Law together with all traditional explanations, statutes, and regulations, as well as the traditions and explanations of the Geonim and the customs which were given, introduced, or recognized from the time of Moses to the conclusion of the Talmud (Preface to the "Mishneh Torah"). It includes also the ethical ideas, the moral teachings, and the doctrinal principles which were traditional or which had been established by the sages or adopted by general consent.