והיה עקב תשמעון את המשפטים האלה ושׁמרתם ועשיתם אתם ושמר ה’ א-להיך את הברית ואת החסד אשר נשבע לאבתיךָ וכו
Therefore it shall come to pass that if you give heed to these rules, and keep and perform them, your Eternal God will keep the covenant and the kindness that he promised on oath to your fathers
The obvious question is why, if the Israelites did observe the laws that the Eternal commanded them, would their reward not be secure even without the covenant that the Eternal promised to their forefathers?
“Distilling his speech like the dew” (הטיף כטל אמרתו Deuteronomy 32:2) our master explained the verse according to the Rambam (Laws of Kings 11:9) 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 considered a resident stranger and is not included among the righteous of the nations.”
The Keseph Mishneh tried unsuccessfully to find the Talmudic source from which the Rambam deduced this proposition. But our Master did find a source in the Talmud (Avodah Zarah 2b) where the verse (Habakkuk 3:6): “ראה ויתר גוים” (He looked and shook the nations) is explained as follows:
He saw that the nations did not observe the seven precepts that the sons of Noah had accepted, and seeing that the precepts were no longer being observed, He rose up and released them from their obligation.
The Gemara concludes that this verse means that even if the Gentiles do observe the Noahide laws, they receive no reward for doing so. But everyone must wonder: if the fathers, not wishing to walk in His ways, sinned and violated the seven Noahide laws, why should the children who uphold those laws conscientiously go unrewarded? “בנים אכלו בוסר ושני בנים תקהינה” (if the fathers have eaten sour grapes, should the teeth of the children be set on edge? Jeremiah 31:28). Therefore, the Rambam, In his wisdom, explained 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 only because their own judgment and reasoning led them to do so. Only if they observe those laws because the Eternal commanded them to do so, will they be rewarded by the Eternal.
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 their own reason requires them to do so, the Eternal will not deny them reward for observing his laws benefit, regardless of their reasons, but will reward them, as promised, in the merit of their ancestors.
Now the word “עקב” (because) denotes a reason or explanation, which is why the Scripture writes “עקב תִּשמעון” (because you will give heed). Thus, even if you will observe these laws because you have another motive 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: your Eternal God will keep with you the covenant and the steadfast love which he swore to your fathers to fulfill. That is why He chose their descendants. And their fulfillment of the commandments, whatever their intention in doing so, will be meaningful to and accepted by Him. (שביבי אש)
ואכלת ושבעת וברכת וכו
And you shall eat and be full, and you shall bless your Eternal God
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: “תברך את ה’ אלקיך” (you shall bless your Eternal God); this is similar to the verse (Deuteronomy 22:8): “ועשית מעקה לגגך” (you shall make a parapet for your roof).
And our master says that the comparison between the two verses is inapt, because the latter verse begins “כי תבנה בית חדש” (when you build a new house) so that it is clear that the remainder of the verse “ועשית מעקה לגגך” must be understood as an imperative. But here, the Scripture is providing a narrative of events after entry into the Promised Land, so it is not necessary to understand the verb “וברכת” as an imperative (i.e. תברֵך) rather than as a simple foretelling of the future.
However our master says that the words of our Sages are “כמסמרות נטועים” ) like nails fastened in a secure place Ecclesiastes 12:11), because after this verse, the Scripture says (Deuteronomy 8:11-14): “השמר לך פן תשכח את ה’ אלקיך וכו’ פן תאכל ושבעת וכו’ ורם לבבך ושכחת ” ) take heed lest you forget the your Eternal God . . . lest when you will eat until you are full . . . so that your heart will be lifted up, and you forget your Eternal God). Thus, the following verses show 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 only to warn immediately that, upon becoming fully satisfied, they should take heed not to forget the Eternal? The Sages therefore properly said that verb “וברכת” must be understood as a Divine imperative of the Eternal.
Why, then, did the Scripture not employ the imperative form (תברֵך) instead of the declarative form (וברכת)? 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):
איך לא אשא להם פנים? שאני כתבתי בתורתי “ואכלת ושבעת וברכת” והם מדקדקים עד כזית וכביצה
How 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 your Eternal God,” and they are particular [to say the grace after meals] even if the quantity is but an olive or an egg.
The Scripture therefore writes the commandment in declarative form “וברכת” to bear witness, there being 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) even less than the amount over which they had been 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. (שביבי אש)
ועתה ישראל מה ה א-להיך שאל מעמך כי אם ליראה את ה א ללכת בכל דרכיו ולאהבה אתו ולעבד את ה א בכל לבבך ובכל נפשך
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
See the Ramban who wrote that this entire passage is connected to the end of the next verse which concludes “לטוב לך” (for your own good). 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 ”לשמר את מצות” (to keep the commandments) instead of “ולשמר את מצות” (and to keep the commandments)?
Our master therefore explains 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 mortal beings made of earth, was to straighten their ways and to “לצרוף כבר סיגיהם” (smelt away [their] dross as with lye Isaiah 1:25) to bring them closer to the Eternal to worship Him and to revere Him, so that “ממנה פנה ממנה יתד” (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 to love the Eternal and cling to Him. These commandments are the very “אבן הראשה” (top stone Zechariah 4:7) with which to subdue our sensual nature and to cast off its yoke from upon our necks.
This is the meaning of what the Scripture asks: ” מה ה’ אלקיך שאל מעמך כי אם ליראה את ה’ אלקיך בכל לבבך ובכל נפשך” (what does the your Eternal God require of you, but to fear your Eternal God 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 “”בכל דרכיו” (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. (שביבי אש)