What is "Vehayah ... " referring to?
Rashi: It is referring to "li'Metar ha'Shamayim Tishteh Mayim (in Pasuk 11). 1
Sifsei Chachamim: If you will heed [and properly fulfill] the Mitzvos, "v'Nasati Metar Artzechem"; if not, rain will be withheld (verses 14-17).
Why does the Torah use the double expression "Shamo'a Tishm'u"?
Why does it insert the word "ha'Yom"?
Rashi: The words of Torah should always be new to you, as if you had just heard them that day. 1
What are the implications of "Le'ahavah es Hashem Elokeichem"?
Rashi: 'One should not say "I will learn Torah (or keep Mitzvos) in order to acquire wealth, to be called a Rav or to earn a livelihood - rather all that you do you should do out of love (of Hashem), and the reward will come later.
What are the connotations of "u'Le'avdo b'Chol Levavchem"?
Rashi: Avodah with the heart refers to Tefilah. 1
Having already issued the command "b'Chol Levavecha uv'Chol Nafshecha" (in 6:5), why does it repeat it here?
Ramban: On whose behalf Hashem performs miracles - to send the rain in its right time and to make an abundance of grass grow for the animals, or to shut down the heavens so that no rain should fall, whereas the individual lives on his merits and dies for his sins.
Ramban: But if they are only Beinonim, He does good or bad to them, depending upon their deeds, without miracles, based entirely on the laws of nature.
Above (6:5), it adds "b'Chol Me'odecha." Why does it not say correspondingly here?
Midrash Tanchuma (No'ach 3): Above it discusses one who learns oral Torah. The Torah did not specify its reward, for it is in the world to come. One who loves wealth and physical pleasures cannot properly learn oral Torah, which requires pain and deprivation of sleep. Here we discuss reward of other Mitzvos.
Roke'ach: Here we do not discuss Avodah that requires monetary loss, rather, Torah and Tefilah, so b'Chol Me'odecha does not apply.
Maharsha (Brachos 35b, according to R. Shimon): Here we discuss Tzadikim who are not Tzadikim bi'Me'od (with their money). Therefore, they need to do their own work.
Kli Yakar, Sifsei Chachamim, Parshas Derachim 21: "B'Chol Me'odecha" was needed for one who values his money more than his life. There are such individuals, but the majority of the Tzibur would not be so foolish.
Kol Eliyahu: Above it discusses individuals who serve with all their money, like R. Shimon ben Yochai, who did not engage at all in income. Very few succeeded like this, therefore our Parshah, which discusses a Rabim, omits this. Nefesh ha'Chayim (1:8, footnote) - it is almost not feasible that a Tzibur not engage in income.
Beis ha'Levi (Derushim 7): Had it said b'Chol Me'odechem, we would say that just like Mesiras Nefesh is needed only for three severe Aveiros or Kidush Hashem, the same applies to forfeiting one's money. Therefore this was omitted, to teach that they are different (one must forfeit all his money rather than transgress any Lav, even in private).
Meshech Chachmah: The Sifri (41) explains "b'Chol Levavchem" to mean that Kohanim should not ponder 'does Hashem really need Korbanos?' This does not apply to all your property.
A Tzibur need not serve Hashem with all its money. (We make decrees lest the Tzibur wax poor, e.g. not to redeem captives for more than their value