To learn the entire Torah
Shalom and thank you for your question. You requested sources for the idea that ‘a man must know or learn the entire Torah’.
Halachic authorities say indeed that aside from the obligation to occupy oneself with Torah – which means to learn it, there is an obligation to know it. To this end a person must learn it well, and review this learning many times, in order not to forget it. This is based on the terminology in Deuteronomy 6:7 “And you shall repeat”. The Hebrew word ‘veshinantam’ used here means ‘repeat’, but it is also connected to the root of ‘to sharpen’. The sages of the Talmud derived from this choice of wording that the learning should be in a manner of sharpness, or exactness, to the point where if the person is asked regarding a matter that he learned about, he should be able to answer without hesitation.
Moreover, a person who does not review what he learned and forgets it, is transgressing the prohibition of “Guard yourself and guard your soul verily lest you forget these words” (Deuteronomy 4:9) . According to the authorities know as the Smag (initials of the title of a Halachic work written by Rabbi Moshe of Kochi) and the Smak (initials of the title of a Halachic work written by Rabbi YItzchak ben Yosef of Corbeil) this is a prohibition from the Torah and according to the Rambam, (Maimonides) the prohibition is a Rabbinic one based on the consensus of the sages regarding what is stated in the Torah.
In the Shulchan Aruch HaRav there is a section dealing with laws of learning Torah. In the last section of chapter 3, there is a distinction made between the mitzvah of learning Torah and the mitzvah of knowing Torah. It is explained there that both of these mitzvot are obligatory, however the mitzvah of knowing the Torah exceeds the mitzvah of learning Torah in its importance and virtue, thus in an instance where there is a conflict between the two mitzvot, such as in a situation where a person travels a long distance in order to learn a lot of Torah from a certain teacher and thus is spending less time learning but learning more Torah than if he hadn’t traveled, the quantity of learning that he will be doing will be preferable to the scenario of his staying at home and learning Torah for a greater amount of time. Rabbi Yisrael Salanter (Ohr Yisrael letter 27) writes that it is permissible to take away from Torah learning time in order to acquire greater knowledge. The implication is that the particular teacher who is physically distant from you has the ability to help you acquire knowledge more efficiently than you would be doing on your own or with other teachers.
According to the opinion of the Rambam, (Maimonides), knowing the Torah is an essential part of the mitzvah of learning Torah, as mentioned above, and thus a person is obligated to learn Torah his entire life. It should be pointed out however, that Rabbi Eliezer ben Shmuel of Mitz, author of Sefer Yereim, posits that there are two separate mitzvot involved in the obligation of learning Torah. One is mitzvah 254 of learning and toiling in learning, and the second is mitzvah 414 that one should teach himself and he should be well versed and the knowledge should be specific and accurate. According to this opinion, every time a person invests effort in studying and toiling in Torah learning, he is fulfilling the mitzvah of learning Torah.
To what point is a person obligated in knowledge of Torah?
The obligation to know the Torah involves all aspects of Torah knowledge. (It should be pointed out here that a woman is ‘only’ obligated to learn those parts of Torah which pertain to the mitzvot she is obligated to perform. However this is quite a vast amount of information, and it includes study of topics such as Torah ethics and Chassidic teachings which can help a person achieve love and awe of G-d, since these are Torah obligations incumbent upon women as well as men.) In one responsa of Rabbi Moshe Feinstein (Igros Moshe 14 and 18′ siman 37) regarding the agreement between Yissachar and Zevulun – namely that Yissachar learns Torah and Zevulun provides the economic backing, he writes that “with reference to the obligation of learning Torah, each and every person is obligated for himself to learn the whole Torah and know it”, and he explains that therefore the Rambam (Maimonides) states that a person is obligated to learn Torah until his final day, based on the statement in the Torah (Deuteronomy 4:9) “lest they shall be turned away from your hearts all the days of your life,” and when a person is not actively occupied in learning he forgets what he had learned previously.
To know Torah is to know G-d, because the Torah is the Divine wisdom and Divine will. So we must definitely strive to do our best to connect with it!
