신명기 11:8의 주석

ושמרתם את כל המצות אשר אנכי מצוך היום, the commandment to erect the stones in the Jordan as well as the stones you will take with you from the Jordan on which you will inscribe the Torah for the benefit of future generations so that the memory that these events really happened will be preserved.

ושמרתם את כל המצוה..למען תחזקו "You shall keep all the commandment in order for you to be strong, etc." Moses advances this argument against the people who suggested a temporary neglect of Torah study, something which physically weakens those who pursue it with intensity. The argument was that they had to husband their physical strength in order for them to conquer the Canaanites. Compare Sanhedrin 26 describing Torah study as a physically debilitating experience based on the word תושיה in Isaiah 28,29. I have mentioned previously that whenever Moses uses the expression כל המצוה in the singular he refers to Torah study. The reason Moses used the expression ושמרתם here, an expression associated with the observance of negative commandments is that neglect of Torah study would be considered a violation equal to transgressing a negative commandment. Moses concludes our verse by saying: "in order that you will be strong" to tell you that far from weakening you, Torah study and מצוה-performance will strengthen you in the forthcoming war by G'd. This is also the meaning of Proverbs 8,14: אני בינה לי גבורה, "once I have acquired insight (through Torah study) courage and strength will be mine."

VV. 8 u. 9. ׳ושמרתם וגו. Ebenso wird die Kap. 10, 12 f. und Kap. 11. 1 in einzelnen Anforderungen vergegenwärtigte Aufgabe Israels hier in einen Gesamtbegriff, den der Mizwa zusammengefasst: es ist die Verpflichtung, für deren Lösung Israel die besondere Stellung inmitten der Völker erhalten hat und nun den dafür bestimmten Landesbesitz antreten soll. למען תחזקו: in dieser שמירת המצוה liegt die Quelle ihrer Kraft und ihrer allen Schwierigkeiten obsiegenden Stärke, sowie die Bedingung der Dauer ihrer Zukunft auf dem Boden dieses Landes. —זבת חלב ודבש (siehe Schmot 3, 8).

למען תחזקו ”in order that you be strong;” Moses does not tell the people to observe G–d’s laws in order that they will become strong (physically), for if that were the reason they would be fulfilling the Torah for the sake of the reward in store for them. This is not the proper motive. (Compare Ethics of our fathers chapter 1, mishnah 3) The interpretation of this line is as follows: “perform the commandments out of a feeling of love for the Lord.” The word למען, here does not mean: “in order that,” just as it does not mean “in order that” in verse 21 of our chapter where we read: למען יאריכון ימיך, in the Ten Commandments in chapter 5,16. It means that the reason you must be strong is in order that you can fulfill the commandment required of you. The word is not linked to what follows, but describes a requisite for successful performance of the Torah being not fear of G–d but love of G–d.

למען תחזקו, “in order that you will remain strong;” Moses does not mean that the commandments should be performed in order to strengthen the Israelites’ bodies; it is never recommended that we serve the Lord for the sake of reward on this earth. (Avot, 1,3) What he meant was that performance of the commandments as a whole punctiliously, would ensure that their stay on the ancestral land they were about to be given would endure for many years. (verse 9)