Rabbi Yakov Haber
Avraham Avinu: The Root of All of Avodas Hashem
"Eikev asher shama Avraham b'koli, vayishmor mishmarti, mitzvosai, chukosai, v'torosoi - Because Avraham hearkened to my voice, and he kept my watch, my commandments, my statutes, and my teachings" (Toldos 26:5). With this statement, Hashem assures Yitzchak Avinu of continued Divine protection and the gift of Eretz Canaan promised to Avraham in the merit of Avraham Avinu's actions. Chazal (Yoma 28b) as well as the classic commentaries discuss and debate the precise meaning of the phrases in this verse. The large number of phrases implies something much more than just minimal fulfillment of the Noahide laws. Rashi, based on the Gemara and Midrashim interprets the various phrases as follows: Mishmarti refers to Rabbinic decrees. Whereas mitzvosai allude to mitzvos sichliyos, "rational" commandments which would have been kept by moral individuals even without specific Divine command, "chukosai" refer to mitzvos shim'iyos, laws without known, "rational" reasons. Finally, "torosoi" means Torah sheb'al peh and halacha l'Moshe miSinai. Ramban explains that the premise of this interpretation is that Avraham literally kept the entire Torah which had been revealed to him through ruach hakodesh before it was given as an eino m'tzuveh v'oseh, on a voluntary basis.
However, Ramban additionally interprets the verse l'fi p'shuto, according to its simple meaning, differently. Mishmarti refers to belief in Hashem, guarding this belief in his heart, and battling against the prevalent corrupted views of the idolaters of his time causing many to adopt the truth of monotheism. Mitzvosai refers to the various specific Divine commands given to Avraham alone such as to travel to Eretz Cana'an and bring Yitzchak as a korban. Chukosai alludes to following the "ways of G-d" emulating his attributes of mercy and compassion and the like. Torosoi refers to the commandments Avraham Avinu was bound to keep and transmit to his descendants, namely, the seven Noahide laws and the mitzva of mila.
As is usually the case, the p'shat given by Ramban and the d'rash quoted by Rashi and elaborated upon by Ramban complement each other. The Torah given to Klal Yisrael guides every aspect of the human experience. Family life, business matters, prayer, Torah study, festivals and interpersonal relationships are all regulated by myriad dikdukei mitzvos recorded in both the Written and primarily in the Oral Law. But underlying all of these details are the broad themes of Divine service: the love and fear of G-d (referred to by the Zohar as the "wings" of mitzvos without which they do not fly heavenward), imatatio Dei, the emulation of Divine middos in perfecting our character, and wholehearted Divine service (see Eikev 10:12-13).
On a surface level, Avraham Avinu's service of G-d focused primarily on the broad themes expressing his enormous love of G-d demonstrated by his abandoning his entire previous life to travel to the "land which I will show you." He expressed his enormous fear of G-d by willingly offering his beloved son as a korban suppressing his instinctive fatherly love for Him. This is the simple meaning of mitzvosai. He perfected his middos surpassing all regular norms of kindness sharing his home and bounty with total strangers and making everyone feel as if they were doing him the favor. He courageously battled against mighty armies to save his relative even though they had previously parted ways physically and religiously and refused to partake of any of the spoils of war. This is the simple meaning of chukosai. But he also loyally kept the details of the specific commandments binding upon him, the sheva mitzvos b'nei No'ach and the commandment of mila. This is the simple meaning of torosoi.
However, Chazal add another dimension to Avraham Avinu's service of Hashem. As one longing and yearning for G-d, he did not suffice with just the broad themes and the specific, few binding commandments given to him. He strove to fulfill everything that he could, even those commandments which were not yet given. Nothing short of the totality of Torah with all of its aspects and details would suffice for Avraham in his attempt to achieve as much perfection and Divine closeness as possible.
With this dual approach, Avraham Avinu, the foundation and root, the rock from which Klal Yisrael was hewn (Yeshaya 51:1), seared into the "spiritual genes" of his progeny the ability to incorporate within their service of G-d all of these aspects: not only the core themes of love and fear of G-d and the striving for character development in emulation of G-d, but also particular attention to dikdukei mitzvos with all of their ramifications. But this would not suffice, he also led the way in maximizing our yearning to go beyond that which is required to do all possible in striving to connect to the One Above.
 See his discussion of the difficulties this raises concerning the conduct of Ya'akov Avinu and others. Also see Gur Aryeh to VaYigash (46:10).
See also Ibn Ezra and Radak.
 See P'nei Y'rushalayim in the Tuv Y'rushalayim edition of the Ramban for an incisive explanation of this three-fold interpretation of mishmarti.