What is the significance of the statement, "HaSh-m appeared to Avraham"?
Seforno: This expression always denotes a level below that of prophecy. 1
The Name of HaSh-m, "Kel," symbolizes strength. What does the Name "Shakai" symbolize?
Rashi: It denotes that HaSh-m 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: HaSh-m is self-sufficient and needs none of His creations to assist Him.
And follow Him with Temimus (see the next Pasuk, 17:2).
Whose explanation the Ramban prefers.
Ramban: HaSh-m 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). HaSh-m 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).
Why did the Avos never refer to HaSh-m directly by His revered four-letter Name, only by HaSh-m E-lokim (spelled irregularly, e.g. 15:8) or Kel Shakai, as opposed to Moshe Rabeinu, who used the Name constantly (and never the Name Kel Shakai)?
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
What is the meaning of HaSh-m'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 - by passing all the tests that I place before you."
Rashi #3 (citing Pirkei d'Rebbi Eliezer): a) Perform the Bris Milah; b) and become spiritually complete; because until now you have been lacking five 3 limbs (i.e. you did not have full jurisdiction over them) - your two eyes, your two ears 4 and the Ever ha'Milah. 5
Ramban: a) Avraham should follow along the path on which HaSh-m leads him - to do His will even before he has been commanded, 6 and to fear Him, and Him alone; b) he should believe that HaSh-m alone is in charge, and not follow the predictions of magicians and sorcerers, 7 as HaSh-m alone has the power to enact and to negate, for better or for worse. 8 He will act for the better on behalf of those who follow the path on which He leads them.
Ibn Ezra: b) Avraham should not query HaSh-m about the Milah.
Seforno: a) Wherever Avraham goes, he should look towards Him; b) because the highest form of perfection that a human being can attain is knowing HaSh-m and going in His ways. 9
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 HaSh-m. Refer to 17:1:4.1.
That is why HaSh-m added a "Hei" to his name, changing it from "Avram" to "Avraham" (Hei equals 5 in Gematriya).
Riva, citing E. Elyakim: Before the Bris, his eyes and ears could not see or hear HaSh-m. This is why he fell on his face, due to fear of the Shechinah. (Perhaps "see HaSh-m" refers to the image (angel) that the Nevi'im saw when HaSh-m spoke to them (refer to 31:13:152:2). Alternatively, it is "HaSh-m's honor," see Targum Onkelus to the verse, "they saw HaSh-m" (Shemos 24:11)). (PF)
This explains the term "Lefanai," "before Me." Whereas the expression to "follow after HaSh-m" (Devarim 13:5) refers to obeying HaSh-m after the command has been issued.
Hence, the Gemara (Shabbos 156a), commenting on the Pasuk above (Bereishis 16:5), cites HaSh-m as saying to Avraham, "Leave aside your astrology! 'Avram' cannot have children, but 'Avraham' can!"
As HaSh-m 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 Nedarim 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 - two eyes, two ears, and the male organ." In what way was Avraham deficient in these five areas prior to his Bris Milah?
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, HaSh-m 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, HaSh-m made him sovereign was over these chief senses as well, upon which HaSh-m added one of the letters of His Name. 2