What is the significance of the statement, "Hashem appeared to Avraham"?
Seforno: This expression always denotes a level below that of prophecy. 1
The Name of Hashem, "Kel," symbolizes strength. What does the Name "Shakai" symbolize?
Rashi: It denotes that Hashem can supply each of His creations with their needs. Consequently, if Avraham will go in His ways, 1 He will be for him a G-d and a patron (to protect him and provide him with all his needs).
Ramban #1 (citing Moreh Nevuchim); Seforno: Hashem is self-sufficient and needs none of His creations to assist Him.
Chagigah, 12a: Hakadosh-Baruch-Hu said 'I am the One who said to the world 'Enough!' 4
And follow Him with Temimus (see the next Pasuk, 17:2).
Whose explanation the Ramban prefers.
Ramban: Hashem mentions this at this point, to inform Avraham that He rules over the Mazalos. He performs hidden miracles for the Tzadikim, to save them from death, to sustain them in time of famine and to stand by their side in battle, (as He did constantly to the Avraham and the Avos). Hashem would exert His jurisdiction over Avraham's Mazal (which foretold that he could not have children (from Sarah)), and they would bear a son in one year's time. Furthermore, He was now entering a covenant with Avraham and his children forever, that they would be "His portion" and that He personally would lead them (and not leave them under the jurisdiction of any star or Mazal).
Torah Temimah (note 1, citing the Gemara): When Hashem created the world, it began to expand more and more until He scolded it and it stopped.
Why did the Avos never refer to Hashem directly by His revered four-letter Name
Ramban: This is because the Avos prophesied with what is known as "Ispaklarya she'Einah Me'irah" (an unclear vision), whereas Moshe prophesied with "Ispaklarya ha'Me'irah" (a clear vision). 1
The Ramban will clarify this in more detail at the beginning of Parshas Va'era (in Sh'mos 6:2).
What is the meaning of Hashem's words to Avraham a. "His'halech Lefanai;" b. "ve'Heyei Tamim"?
Rashi #1 (citing Targum Onkelus): a. "Cleave to My service;" b) "Be perfect
Mishnas R. Aharon (Vol. 3, p. 117): Perfection is specifically through Milah, which is in the body itself, unlike other Mitzvos.
Because a person who has an Orlah (who is not circumcised) is considered blemished in the eyes of Hashem. Refer to 17:1:4.1.
That is why Hashem added a "Hey" (Gematriya five) to his name, changing it from "Avram" to "Avraham"
Riva, citing E. Elyakim: Before the Bris, his eyes and ears could not see or hear Hashem. This is why he fell on his face, due to fear of the Shechinah. (Perhaps "see Hashem" refers to the image (angel) that the Nevi'im saw when Hashem spoke to them (refer to 31:13:152:2). Alternatively, it is "Hashem's honor," see Targum Onkelus to the verse, "they saw Hashem" (Shemos 24:11)). (PF)
This explains the term "Lefanai," "before Me." Whereas the expression to "follow after Hashem" (Devarim 13:5) refers to obeying Hashem after the command has been issued.
Hence, the Gemara (Shabbos 156a), commenting on the Pasuk above (Bereishis 16:5), cites Hashem as saying to Avraham, "Leave aside your astrology! 'Avram' cannot have children, but 'Avraham' can!"
As Hashem declared when He created man, "Let Us make man in Our form and in Our image!"
QUESTIONS ON RASHI
Rashi writes: "Walk before Me - with the Mitzvah of Milah; and with this [Mitzvah] you will be (physically) complete (Tamim)." Why was Avraham called "Tamim" only though the Mitzvah of Milah?
Maharal (Chidushei Agados Vol. 2, p. 6, to Neearim 31b): Milah is the "Tzurah" (purpose, actualization) of the physical body. 1 The Orlah is the remaining deficiency in that Tzurah, and when that Chomer is removed, one can attain wholeness.
Rashi writes: "Presently, you are deficient in five organs
Gur Aryeh #1 (citing Ran to Nedarim 32b): Without a Milah, one is unable to control his eyes and ears and avoid the sin of seeing or hearing something improper, albeit unintentionally (and the foreskin is in itself repulsive). After the Milah, Hashem gave Avraham control over these areas as well, to be used only for a Mitzvah.
Gur Aryeh #2: Initially, upon hearing or seeing something improper, Avraham would have to battle his Yetzer and overcome the urge to follow it. Though the Milah, these limbs and indeed the Yetzer itself were put under his control.
Maharal (Chidushei Agados Vol. 2, p. 11, to Nedarim 32b): Avraham was able to subdue his Chomer, (his temporal, physical aspect); 1 his lesser physical aspect was simply the motor of his G-dly aspect. When he was circumcised, removing the Orlah, Hashem made him sovereign was over these chief senses as well, upon which Hashem added one of the letters of His Name. 2