The Avot and the Mitzvot
וַיִּשְׁמֹר מִשְׁמַרְתִּי מִצְוֹתַי חֻקּוֹתַי וְתוֹרֹתָי:
He (Avraham) observed My safeguards, My commandments, My decrees, and My Torahs. (Bereishit 26:5)
Rashi to our pasuk quotes the words of Chazal who derive from the various terms mentioned here that Avraham Avinu kept all of the Taryag Mitzvot, including the mitzvot d’Rabbanan. There are similar statements in the Midrash concerning the other Avot as well.
In light of this tradition from Chazal, let us consider the words of the Rambam in perek 9 of Hilchot Melachim (halachah 1), who discusses the specific mitzvot that were introduced in the lives of the Avot, in addition to the seven mitzvot with which Bnei Noach were already commanded:
Avraham came and was commanded in addition to these regarding milah, and he prayed shacharit. Yitzchak separated maasrot and added an additional tefillah toward the end of the day, and Yaakov added gid hanasheh and prayed arvit.
The Added Mitzvot of Avraham, Yitzchak, and Yaakov
The first thing to note regarding the above words is that while the Rambam describes Avraham as being “commanded” regarding milah, when it comes to Yitzchak he states only that he “separated maasrot.” The reason for this differentiation lies very simply in the way these two mitzvot are referred to in the relevant pesukim. In Parshat Lech Lecha the pasuk states clearly that Hashem commanded Avraham to perform the mitzvah of milah. In contrast, the source in the pasuk for Yitzchak separating maasrot is in the words that describe the harvest as having exceeded his estimation of its yield one hundredfold (Bereishit 26:12) “וַיִּמְצָא בַּשָּׁנָה הַהִוא מֵאָה שְׁעָרִים.” Chazal inform us that the reason Yitzchak estimated how much his fields would produce was for purposes of separating maaser. Therefore, since the pasuk describes Yitzchak as being involved in separating maasrot, but, unlike Avraham, does not mention anywhere that he was commanded by Hashem to do so, the Rambam simply presents this mitzvah as something that Yitzchak did.
We may ask, if Yitzchak was not commanded regarding maasrot but performed that mitzvah anyway, in what way does this differ from the rest of the Taryag Mitzvot? We have a tradition that the Avot kept the entire Taryag Mitzvot even without being commanded to do so, in which case, what was special about Yitzchak fulfilling the mitzvah of maasrot on a voluntary basis? The Lechem Mishneh (Hilchot Melachim ibid.) answers that the tradition regarding the Avot and the Taryag Mitzvot refers to them performing those mitzvot as individuals. In contrast, the specific mitzvot which the Rambam lists as being introduced by the Avot [milah, maasrot and gid hanasheh] were instituted by them for their household and descendants as well.
However, in light of the distinction between commandment and narrative in the pasuk, we now come to consider the way the Rambam describes the third Av and the mitzvah that he introduced: “And Yaakov added gid hanasheh.” Here, we seem to have a problem. The pasuk states regarding gid hanasheh (Bereishit 32:33), “עַל כֵּן לֹא יֹאכְלוּ בְנֵי יִשְׂרָאֵל אֶת גִּיד הַנָּשֶׁה — therefore, Bnei Yisrael shall not eat the gid hanasheh.” This is the source in the Torah for the prohibition of gid hanasheh, which means that the words “לֹא יֹאכְלוּ” are clearly a command, and not merely a description. If so, why does the Rambam say that Yaakov “added” gid hanasheh, and not that he was commanded to do so?
The answer is that although these words are indeed a command, they are a command directed toward Bnei Yisrael who received the Torah at Har Sinai. All mitzvot written in the Torah are addressing Bnei Yisrael from the point of Matan Torah onward. The only time a mitzvah in the Torah is understood as binding on anyone before Matan Torah is if the pasuk states that Hashem commanded that person, for example, when Hashem commanded Avraham regarding milah. When it comes to gid hanasheh, the Torah does not state that Hashem commanded Yaakov that his children should not eat from it. Therefore, even if these words are understood halachically as a mitzvah, the “Bnei Yisrael” referred to in the pasuk are Am Yisrael who received the Torah.
At the same time, however, the pasuk is written in the context of Yaakov himself. This tells us that in addition to understanding these words as a command to us, we are also to understand them as a description of the “sons of Yisrael” [i.e., Yaakov] himself. This is the source for the idea, on the level of pshat, that this mitzvah was introduced by Yaakov, albeit in a voluntary capacity, hence the Rambam writes regarding Yaakov as well that he “added” gid hanasheh.
The Avot and Tefillah
In this vein, it is also significant to note that alongside the three mitzvot d’Oraita mentioned by the Rambam with respect to the Avot, he also mentions the mitzvah of tefillah in connection with each Av; Avraham introduced shacharit, Yitzchak minchah, and Yaakov maariv. Here, too, the Rambam is taking his cue from the fact that these tefillot are referred to in the pesukim dealing with the Avot.
Although the three daily tefillot are d’Rabbanan in nature, they nevertheless played a significant role in the lives of the Avot, who were dedicated to preparing the way for their descendants to “graduate” from the status of Bnei Noach to that of Bnei Yisrael. The mitzvot represent the aspect of our connection with Hashem where He speaks to us. No less an important part of this relationship is the realm of tefillah, where we reach up toward Hashem and speak to Him. This, too, was part of the groundwork laid for the future Am Yisrael, and as such the three daily tefillot take their place alongside the mitzvot d’Oraita introduced by the Avot.
It is noteworthy to further point out that the fact the tefillot of the Avot are derived from pesukim in the Torah has ramifications in the realm of halachah as well. As we mentioned, the three daily tefillot are d’Rabbanan in nature. Nonetheless, the Gemara (Taanit 28a) states regarding tefillat minchah that it enjoys a higher status than other mitzvot d’Rabbanan and explains that this is because tefillat minchah is d’Oraita! Rashi (ibid.) explains that the reason the Gemara refers to minchah as “d’Oraita” is because it is derived from a pasuk in the Torah. We see from here that even a mitzvah d’Rabbanan attains a higher status when it is rooted in Torah Shebichtav. Moreover, this is true even if the pasuk from which it is derived is not written as a tzivui (command), but as a sippur (narrative). None of the pesukim quoted by the Gemara as sources for tefillah mention that Hashem commanded any of the Avot to pray; they merely relate that the Avot did so. Nonetheless, this is sufficient to elevate the level of the mitzvah of tefillah. All of this gives us further appreciation of the role of Torah Shebichtav in establishing the status of mitzvot — even mitzvot d’Rabbanan!
The Avot and Mitzvot D’Rabbanan
It remains for us to examine the statement of Chazal that the Avot observed not only the mitzvot d’Oraita, but also the mitzvot which are d’Rabbanan. This is quite a challenging idea. When it comes to mitzvot d’Oraita, it is possible to understand how the Avot were able to fathom these mitzvot even without being told about them. After all, Chazal have stated elsewhere that “אסתכל באורייתא וברא עלמא — Hashem looked into the Torah and created the world.” (Zohar HaKadosh, Parshat Terumah) This means that the mitzvot of the Torah are the spiritual underpinnings and the “blueprint” of the world. This being the case, the Avot, with their exceptional spiritual perception, were able to ponder the nature of the world and through that to “work backward” and fathom the various mitzvot of the Torah. However, the mitzvot d’Rabbanan are presumably not part of the essential makeup of the world; they are things that were added to the mitzvot of the Torah by the Rabbanan at various stages. How did the Avot come to know about these mitzvot? Shall we say that they saw through Ruach HaKodesh the mitzvot and halachot that the Rabbanan would later add on?
While this is indeed possible, what appears more correct is that the situation is actually reversed. The mitzvot d’Rabbanan were not the product of the Avot looking forward, but of Chazal looking backward! In order to understand how this might be, we must examine the relationship between the mitzvot of Chazal and those of the Torah. The guiding principle here is that the mitzvot of the Torah represent the most basic level of fulfilling that mitzvah. The Rabbanan, through their safeguards and enactments, sought to bring Am Yisrael to a higher and more enhanced level of fulfillment of the mitzvot of the Torah. Where might they look to discover what these exalted levels of avodat Hashem look like? The answer is; the lives of the Avot!
In all that they did, the Avot lived their lives with complete devotion and dedication toward fulfilling ratzon Hashem, and it is to this exalted madreigah that every Jew must aspire, as Chazal tell us (Tanna D’vei Eliyahu perek 25), “A person is obligated to say, ‘When will my deeds equal those of my fathers, Avraham, Yitzchak, and Yaakov?’” Thus, when we say that the Avot kept mitzvot d’Rabbanan, it means that their lives served as the inspiration for the various mitzvot that the Rabbanan introduced later on.
V’El Maalat Avotam Yashuvu
The Ramban, in his introduction to his peirush on Chumash Shemot, describes the state of Geulah as one where Am Yisrael have returned “אל ארץ אבותם ואל מעלת אבותם ישובו — to the land of their fathers, and to the exalted level of their fathers.”
Moreover, as we have noted elsewhere, the Avot enjoyed — as individuals — the status of Am Yisrael. This means that, as a People, we have already experienced the lofty madreigah of the Avot at the time when the concept of Am Yisrael existed within the Avot. Hence, the aspiration to “return to the level of their fathers” is ultimately one of returning to the level on which we ourselves have already existed.
This should serve to give us a new and deeper appreciation of Chumash Bereishit, which is devoted in large part to recounting the lives of the Avot. Although on the one hand we do not learn many halachot d’Oraita from Bereishit, on the other hand a careful study of the lives of the Avot — not through midrash halachah but through pshuto shel mikra! — can yield a picture of what complete avodat Hashem looks like, which in time became the basis for mitzvot d’Rabbanan.
 [The seven mitzvot of Bnei Noach.]
 See Parshat Vayishlach, Chapter 23, for a discussion of this idea at length.
 See Berachot 26b where each tefillah is derived from the relevant pasuk relating to each Av.
 See Ohr Sameach to Hilchot Talmud Torah, perek 1, halachah 2.
 [As the Rav put it in Hebrew in his unique way: האבות לא כיונו אל חז"ל, הם כיונו את חז"ל]
 See Parshat Lech Lecha, Chapter 8.