What is "Ka'asher Tzivcha Hashem Elokecha" here referring to?
Rashi (citing Sanhedrin, 56b): It (too) is referring to Marah, 1 where Hashem first commanded Yisrael about Kibud Av va'Eim. 2
Oznayim la'Torah: Having witnessed the Greatness and he greatnes of Hashem Kavod of Hashem (the third partner in teir formation), Hashem instructed them to honor the first two partners (their father and mother) as well. 3
See Torah Temimah, note 4.
See Ba'al ha'Turim. Strangely, in Sh'mos, Rashi omits Kibud Av va'Eim from the list of Mitzvos that were commanded in Marah, as the Ramban points out. Refer to Sh'mos, 15:25:3:1*.
As opposed to the NOchrim, who only acknowledge after they see how Hashem commanded the Mitzvah of Kibud Av va'Eim - which they oftens tend to observe meiiculously. Se Oznayim la'Torah DH 'Kabeid es Avicha ve'es Imecha ... '.
What are the connotations of the words "Ya'arichun Yamecha u'Lema'an Yitav lach ... "?
Ramban (in Yisro, Sh'mos 20:12) and Seforno: "Lema'an Ya'arichun Yamecha" refers to Olam ha'Ba (The world that lasts a long time), whereas "u'Lema'an Yitav lach ... " means that Hashem will also reward Kibud Av ... with a good life 1 in this world ... . 2
Kidushin 39b: They both mean in the world that is [totally] good and long 3 - the world to come. 4
Tanchuma Eikev 3: They both refer to this world.
Yerushalmi KIdushin, 1:6: If long life and goodness are the reward for Kibud Av va'Eim, which is merely a sort of repayment, 5 how much more so for a Mitzvah which entails a loss of pocket or danger to one's life (such as T'rumos and Ma'asros or B'ris Milah - Torah Temimah).
Refer to Sh'mos 20:12:4:1,4 & 6 and notes, and refer to Sh'mos 20:12:153:1.
Seforno: Seeing as the Mishnah in Pe'ah, 1:1. includes Kibud Av va'Eim in the list of Mitzvos for which one eats the fruits in this world, and the principle in the World to Come.
Ramban: See Tehilim, 85:13. Kidushin, 40a: Hence, Kibud Av va'Eim is listed among the Mitzvos the fruits of which one receives in this world, but the principle is kept for th world to come. See Torah Temimah,note 9.
See Torah Temimah, note 8, who reconciles this with the fact that many Parshiiyos in the Torah speak about reward in this world.
Otherwise, how would we reconcile the Pasuk with a case where a father asked his son to climb on to the roof to bring him some young doves, which the son did, after sending saway the mother, only, on the way down, he fell off the ladder and died - a scene which R. Ya'akov, the author of this answer - witnessed with his own eyes?
See Torah Temimah, note 10.
Why did the first Luchos not contain "Lema'an Yitav lach"?
Bava Kama, 55a: Because they were destined to be broken. 1
And would have therefore have indicated that the 'Tov' with which Yisrael was blessed would come to an end.
Why does the Torah write here "Ya'arichun Yamecha", wheres regarding Shilu'ach ha'Ken it writes "ve'Ha'arachta Yamim" (22:7)?
Riva: The conjugation "Ya'arichun" means that others will cause it, indicating that if children honor their parents, they (the parents) will Daven that they should live a long life.
In Bava Kama, 54b, R. Chanina ben Agil asked why was "Tov" mentioned in the second Luchos but not in the first, and R. Chiya bar Aba was unsure whether it was said. Did he not know the Pasuk? And the Gemara concludes that it is lest 'good' cease from Yisrael, for the first Luchos would be broken. Why is there no concern lest "Ya'arichun Yamecha (your days will be lengthened)" cease?
Refer to Sh'mos 20:12:153:1 and see Torah Temimah, note 12.