וְהָיָה עֵקֶב תִּשְׁמְעוּן אֵת הַמִּשְׁפָּטִים הָאֵלֶּה וּשְׁמַרְתֶּם וַעֲשִׂיתֶם אֹתָם וְשָׁמַר ח"א אֶת הַבְּרִית וְאֶת הַחֶסֶד אֲשֶׁר נִשְׁבַּע לַאֲבֹתֶיךָ וכו'
Therefore it shall come to pass, if you give heed to these judgments, and keep, and do them, that the Lord your G-d shall keep with you the covenant and the mercy (Deuteronomy 7:12)
The question is obvious: why, if the Children of Israel observed the laws that the Eternal commanded them, would their reward not be secure even if the Eternal did not remember in their behalf the covenant that He made with their forefathers?
Our master "distilled his speech like the dew" (הטיף כטל אמרתו Deuteronomy 32:2) and explained the verse according to the Rambam (הלכות מלכיס פרק ט הלכה יא) who said: Everyone who accepts the seven Noahide Laws has a portion in the world to come, provided that one accepts and performs them because the Holy One Blessed Be He commanded to do so in his Torah. But if one performs those commandments because of his own judgment, he is not a ger toshav and is not included among the righteous of the nations.
The Keseph Mishneh probes deeply to inquire from where in the Talmud the Rambam deduced this. But our Master found a source in the Talmud (Avodah Zarah 2b) where the verse (Habakkuk 3:6): "He looked and shook the nations" (רָאָה וַיַּתֵּר גּוֹיִם) is explained as follows:
He saw that the nations did not observe even the seven precepts which the sons of Noah had taken upon themselves, and seeing that they did not observe them, He stood up and released them therefrom.
The Gemara concludes that this means even if the Gentiles observe the Noahide laws, they receive no reward for doing so. Now every intelligent person must ask: if the fathers, not wishing to walk in His ways, sinned and did not observe the seven Noahide laws, why should the reward of the children who uphold those laws conscientiously be withheld? "Because the fathers have eaten sour grapes, should the teeth of the children be set on edge?" (Jeremiah 31:28) The Rambam, therefore, found it appropriate to explain, in his wisdom, that the Gemara meant that in "releasing" the Gentiles from the seven Noahide laws, the Eternal decided that the Gentiles would not be rewarded for observing those laws if they did so solely because of the dictates of their own judgment and reasoning. It is only if they observe those laws because the Eternal commanded them to do so that the Eternal will reward them.
However, that is not how Eternal conducts Himself with the Children of Israel who are sustained by the merit of their ancestors. For even if they observe His statutes and keep His laws only because of the dictates of their own reason, should they still succeed in finding any reason to observe His laws and statutes, the Eternal will not deny them benefit but will give them their reward in the merit of their ancestors as He promised them.
Now the word " עֵקֶב" (because) denotes a reason or explanation, which is why the Scripture writes "וְהָיָה עֵקֶב תִּשְׁמְעוּן" (and because you will give heed). Thus, even if you will observe these laws because of some ulterior motive within you that causes you to observe and to fulfill them, you will, nevertheless, still be able to partake of the reward. And the Scripture then explains the reason: "the Lord your G-d will keep with you the covenant and the steadfast love which he swore to your fathers to keep." He therefore chose their descendants. And their fulfillment of the commandments, whatever their intention in doing so, will be meaningful and acceptable to Him.
וְאָכַלְתָּ וְשָׂבָעְתָּ וּבֵרַכְתָּ וכו'
And you shall eat and be full, and you shall bless the Lord your G-d (Deuteronomy 8:10)
The Ramban wrote as follows: when you will eat and you will be satisfied in this good land, you will, as a result, bless the Eternal. However, the tradition of our Sages is that the verse prescribes a positive obligation. And the meaning is therefore: "you shall bless the Lord your G-d" (t'vareikh et ha-Sheim Eloqekha) and this is similar to the verse (Deuteronomy 22:8): "you shall make a parapet for your roof" (וְעָשִׂיתָ מַעֲקֶה לְגַגֶּךָ).
And our master says that the comparison between the two verses is not accurate, because the latter verse begins "when you build a new house," so that it is clear that the remainder of the verse "v'asita ma'akeh l'gagekha" ("you shall make a parapet for your roof" must be understood as an imperative.) But here, the Scripture is providing a narrative of future events after the entry into the Promised Land, so there is no necessity to understand the verb "וּבֵרַכְתָּ" as an imperative i.e. תְּבָרֵ֪ךְ rather than as a simple foretelling of the future.
However our master says that the words of our Sages are "like nails fastened" (Ecclesiastes 12:11) in a secure place and they properly proved their interpretation, because after this verse, the Scripture says (Deuteronomy 8:11-14): "Take heed lest you forget the Lord your G-d . . . lest when you have eaten and are full . . . then your heart will be lifted up, and you forget the Lord your G-d." Thus, from the following verses it is evident that, by eating and becoming satisfied, one naturally tends to forget, not to bless, the Eternal. So how could the Scripture have contradicted itself by first foretelling that, after eating and becoming satisfied, the people would be aroused on their own to thank the Eternal but then immediately thereafter warn that if they become well satisfied they should take care not to forget the Eternal? The Sages therefore properly said that the verb "וּבֵרַכְתָּ" (you will bless) must be understood as an imperative, as a Divine commandment of the Eternal.
Why, then, did the Scripture not employ the imperative form (תְּבָרֵ֪ךְ) instead of the declarative form (וּבֵרַכְתָּ)? The choice of the declarative may be attributed to the desire of the Scripture to provide a hint for the following saying of the Sages (Berakhot 20b):
And shall I not lift up My countenance for Israel, seeing that I wrote for them in the Torah, "and you will eat and be satisfied and bless the Lord your G-d." and they are particular [to say the grace after meals] if the quantity is but an olive or an egg.
The Scripture therefore writes "you shall bless" in the declarative form "וּבֵרַכְתָּ" to bear witness, as there is nothing for which no hint can be found in the Torah, that in the future they will recite the blessing also for a quantity of food (equal to an olive or an egg) less than that over which they were Biblically obligated to recite a blessing. In this light, we can explain away an objection that might have been raised: if one is not obligated to recite a blessing, then it is a blessing in vain. However, according to what we have said, since the Torah provided a hint for the making of a blessing on a lesser quantity of food, such a blessing is not a blessing in vain.
וְעַתָּה יִשְׂרָאֵל מָה יְהוָה אֱלֹהֶיךָ שֹׁאֵל מֵעִמָּךְ כִּי אִםלְיִרְאָה אֶת ה"א לָלֶכֶת בְּכָל דְּרָכָיו וּלְאַהֲבָה אֹתוֹ וְלַעֲבֹד אֶת ה"א בְּכָל לְבָבְךָ וּבְכָל נַפְשֶׁךָ
And now, Israel, what does the Lord your G-d require of you, but to fear the Lord your G-d, to walk in all his ways, and to love him, and to serve the Lord your G-d with all your heart and with all your soul (Deuteronomy 10:12)
See the Ramban who wrote that this entire passage is connected to the end of the next verse which concludes "for your own good" (לְטוֹב לָךְלִשְׁמ). But our Sages, as is well known, did not share this interpretation. And it is obscure why, according to the Ramban, if it is all one idea, the Scripture splits it into two verses. Moreover, why does the second verse begin "to keep the commandments" (לִשְׁמֹר אֶת מִצְוֹת) instead of "and to keep the commandments" (וּלִשְׁמֹר אֶת מִצְוֹת)?
It therefore appears to our master that the only reason that the Eternal gave us His commandments and his laws, commandments pertaining to human beings that are all concerned with the conduct of people made of earth, was to straighten their ways and to "smelt away [their] dross as with lye" (Isaiah 1:25) to bring them closer to the Eternal to worship Him and to revere Him. "Out of them shall come the cornerstone, out of them the tent peg" (Zechariah 10:4) with which to take and elevate these clumps of clay so that they should love the Eternal and cling to Him. These commandments are the very "top stone" (Zechariah 4:7) with which to subdue our sensual nature and to cast off its yoke from upon our necks. This is what the Scripture asks: "What does the Lord your G-d require from you, but to fear the Lord your G-d . . . to love Him, to serve the Lord your G-d with all your heart and with all your soul?" For the desire of the Eternal and His longing when He gave us the Torah was that it should purify human beings originated from dust and elevate them to serve Him with all their hearts and all their beings. And the Scripture says "in all His ways" to teach us that the duty of the heart is to remove from within ourselves the heart of stone and to replace it with a heart of flesh so that we may travel in the ways of the Eternal. As the Sages said, just as He is merciful, so also should you be merciful; just as He is gracious, so too should you be gracious. These are the ways of the Eternal Being.
But in the second verse, the Scripture is referring to those positive commandments that a person must perform with his own hands, and to the negative prohibitions from which one must turn away and stand at a distance. The verse says: "to keep the commandments and statutes of the Lord, which I command you this day for good," which means that the Eternal enlarged and magnified the Torah with commandments governing our conduct for our own good in order that we might more easily achieve our ultimate goal to revere the Eternal and to love Him and to become complete in our characters and our personalities. For these positive and negative commandments will help you to purify and to elevate yourselves, enabling you to revere and love the Eternal and to attain a lofty and exalted character.