Seeing as, at Har Sinai, Moshe had initially maintained that "Erech Apayim" should be confined to Tzadikim, why did he mention it here, where the people were Resha'im?
Rashi (citing Sanhedrin, 111a): Becuse, when Moshe suggested that 'Erech Apayim' is fitting for Tzadikim and that Resha'im should perish, Hashem replied that it is even for Resha'im. 1 Consequently, when Moshe mentioned "Erech Apayim" here, and Hashem reminded him of what he had said, Moshe countered 'But You said even for Resha'im!'
See Torah Temimah, citing Sanhedrin, Ibid., and note 11.
What are the connotations of "ve'Rav Chesed"?
Rashi (in Ki Sisa Sh'mos, 34:6): It is written with reference to people who need lovingkindness but who do not have sufficienrt merits to deserve it.
Does Hashem 'visit' the sins upon the third generation or the fourth generation?
Seforno: If the third generation sin more than their parents, then Hashem will destroy them immediately; 1 whereas if they sin to the same extent as their parents, He will wait for the fourth generation before destroying them.
Seforno: Since there is no hope that they will do Teshuvah.
Why did Moshe omit the Midos of "Rachum and Chanun"?
Ramban and Moshav Zekenim #1: It is because he knew that the Midas ha'Din was facing them, and that full pardon was out of the question, so he merely asked that Hashem not kill them all at once only via a plague over a long period. 1
Da'as Zekenim #2 (in Pasuk 17): "Rachum" goes together with "Chanun", which in turn, implies a gift, and Moshe was requesting a pardon, and not a gift.
And it is for the same reason that he omitted one 'Hashem' and 'Keil' - because they have connotations of mercy, bearing in mind that they had all sinned and had not done Teshuvah - See Oznayim la'Torah, who comments further that, whereas by the Golden Calf Moshe recited the thirteen Midos after the sinners had been punished and the people had done Teshuvah, here he recited them while Hashem's anger was still burning, which is why he was careful to omit some of the Midos in the way that we explained. See Oznayim la'Torah, who elaborates.
Why did Moshe omit the Midos of 'Emes' and 'Notzer Chesed la'Alafim' here?
Ramban (on Pasuk 17): Because according to the Midah of Emes, they ought to have been destroyed (since they had not repented 1 ); whereas 'Notzer Chesed la'Alafim' is based on Z'chus Avos, and Z'chus Avos was not appropriate here, since the people were rejecting the Avos and the gift (of Eretz Yisrael) which the Avos yearned for. 2
Hadar Zekenim and Da'as Zekenim (in Pasuk 17): 'Emes' would entail fulfilling His word "Akenu ba'Dever ve'Orishenu" (in Pasuk 12) and because Hashem should not come with true judgment against them; whereas 'Notzer Chesed' did not apply, since they did not do Chesed - they sinned.
Moshav Zekenim: Also at the Eigel, Yisrael were liable, and Moshe mentioned 'Emes'! There, Hashem said "Hanichah Li? va'Achalem" (Sh'mos 32:10), which implies that it all depends on Moshe', so he was not concerned. (Above on this Pasuk, he said that Moshe said the Midos after the Eigel after they repented ? Refer to 14:18:151:2 and note ? PF)
Ramban: Consequently, the Tefilah that he recited in Sh'mos 32:13 would have been totally out of place here.
What are the implications of "Poked Avon Avos al Banim"? Why did Moshe insert it?
Ramban (in Pasuk 17) and Moshav Zekenim: It implies that, if Hashem will not forgive them, at least allow their punishment to be passed on to their children. 1
Da'as Zekenim and Hadar Zekenim: Because it is a Midah of mercy, inasmuch as He does not punish until the fourth generation. 2
Why did Moshe omit one mention of "Hashem" and "Keil"?
Da'as Zekenim (on Pasuk 17) and Hadar Zekenim: He mentioned the first "Hashem", which stands for mercy, but not the second, which stands for Din, whereas "Keil" refers to a judge.
Moshav Zekenim (citing the Ramban): One 'Hashem' pertains to after the sin but before Teshuvah; the other, to after Teshuvah. Following the sin of the Eigel, Yisrael had done Teshuvah, so Moshe 1 mentioned 'Hashem' twice; whereas here they had not done Teshuvah, so he only mentioned it once. 2
One 'Hashem' was not relevant, since it pertained to before a person sins. 3
Why did Moshe omit "ve'Chata'ah"?
Ramban (in Pasuk 17) and Moshav Zekenim: Because "ve'Chata'ah" implies Shogeg, and Yisrael in this instance were Meizid. 1
Da'as Zekenim (on Pasuk 17) and Hadar Zekenim: As Moshe explicitly told them in Pasuk 9 "Ach ba'Hashem Al Timrodu".
Why did Moshe insert "ve'Nakeh Lo Yenakeh"?
According to Rashi #1 (in Ki Sisa Shmos, 34:6): Because it is also Hashem does not punish all in one go, but exacts punishment bit by bit.
According to Rashi #2 (in Ki Sisa Shmos, 34:6, citing the Chachamim) Tarfum Onkelos and Targum Yonasan: To teach them that they would only achieve pardon if they did Teshuvah, but not oif they don't.
Hadar Zekenim: Also it is a Midah of mercy, since it implies that He does not exterminate sinners from the world. 1
Da'as Zekenim: Like we find in Yirmiyah 30:11 "ve'Yisarticha? Lo Anakeka". Se Oznayim la'Torah, who proves this explanation from Pasuk 18. Refer to 14:18:152:1.
