The main study of one who proposes to become a rabbi is the Talmud. Let me explain: The Talmud comprises sixty books which contain all the Jewish civil canonical laws. The number of these laws is legion. One commandment of the Decalogue, “Six days shalt thou labor…but the seventh day is the Sabbath of the Lord thy God,” is explained by the Talmudic doctors in four hundred and sixteen sections, each section containing from eight to twenty divisions, giving the most minute directions for the observance of the Talmudic Sabbath laws.
The Jews believe that all these, as well as the many thousands of rules and precepts appointed by the wise men, are as holy and binding as the ten commandments because they have a tradition that the Pentateuch, which Israel was commanded to put in writing, is only the text, and the Talmud is the explanation God gave to Moses by word of mouth on Mount Sinai. Moses, when he gave written law, delivered also this oral law to the people, who repeated it until fixed in their memory.
Each generation transmitted it to the next, until about the Fourth Century ad, when the different laws and discourses were collected, compiled, written down, and completed. Ever since that time, the Jews make these books their chief study, day and night, not only for the sake of knowing the different laws, or of becoming rabbis, but because they believe that in studying the Talmud they render the greatest service to God, as the Talmud itself says, “There is no more meritorious study than that of the oral law.” So I was a very good boy when I devoted nearly all my time to the Talmud and almost none to the Prophets.