Commentary for Deuteronomy 11:18

ושמתם את דברי AND YE SHALL PLACE MY WORDS [UPON YOUR HEART] — Even after you have been banished make yourselves distinctive by means of My commands: lay Tephillin, attach Mezuzoth to your doorposts, so that these shall not be novelties to you when you return. Similarly does it state, (Jeremiah 31:21) “Set thee up distinguishing marks” (Sifrei Devarim 43:34).

THEREFORE SHALL YE PUT THESE MY WORDS IN YOUR HEART. “Even after you have been exiled, be distinguished by the commandments. Put on the T’fillin, attach a Mezuzah [to the doorpost of your home], so that they will not be novelties to you when you return to the Land. And so Scripture states, Set thee up waymarks.”³²⁹Ibid., Verse 21. Jeremiah lived in the time when the people were about to go into the Babylonian exile. His prophecy was thus a warning that they were to retain their distinctiveness through the commandments. This is Rashi’s language. Now I have already written³³⁰Above, 4:5. on the meaning of this matter, that these commandments [the T’fillin and the Mezuzah mentioned by Rashi] are personal obligations and, as such, their laws apply in all places just as in the Land!³³¹If so, why are these commandments, which are obligatory everywhere, called “waymarks” in the exile? But there is in this Midrash etc. But there is in this Midrash³³²Rashi’s text comes from the Sifre, Eikev 43. Hence Ramban refers to it as “this Midrash.” a profound secret, and I have already alluded to it.³³³See Vol. I, pp. 294, 331-332; Vol. III, p. 272. Now he repeated these commandments about the T’fillin, the study of the words of the Torah, and the Mezuzah, a second time³³⁴See above 6:7-9. in order to allude to this analogy, that we shall be obligated to observe them after being exiled from the Land of Israel. From these [texts] we learn that all commandments that are personal obligations are binding in all places and that, outside the Land of Israel, we are exempt from duties which apply to ground, such as heave-offering and tithes. So it is interpreted in the Sifre.³³⁵Sifre, Eikev 44. And the intent of this interpretation is suggested by the fact that he placed the expression therefore shall ye put [these my words in your heart] next to [the verse], and ye shall perish [quickly from off the good Land³³⁶Verse 17. thus clearly intimating that even after ye shall perish from off the good Land you shall still put these My words in your heart]. But the main reference of the verse [even regarding personal obligations] applies to the Land, as it is written, that your days may be multiplied, and the days of your children, upon the Land;³³⁷Verse 21. or it may be that the verse is stating: “that your days may be multiplied, so that you will return [to the Land] and you will prolong your days on it forever.”³³⁸According to the first interpretation, the main reference of the verse put these My words in your heart is to the Land of Israel; this is evidenced by the concluding verse, that your days may be multiplied …upon the Land. According to the second interpretation the former verse has reference to the exile, while the second verse states the reward, that your days may be multiplied, so that you return and live upon the Land.
In line with the plain meaning of Scripture, it is possible that he comes to add here the expression to speak of them,³³⁹Verse 19: And ye shall teach them unto your children ‘to speak of them.’ for there [in the first charge to the individual] he commanded and ‘thou’ shalt speak — you yourself — of them when ‘thou’ sittest in thy house,³⁴⁰Above, 6:7. and here [in the charge to the community he stated that we are to teach the words of Torah to our children until they speak of them always. So also he added here and ye shall ‘teach’ them,³³⁹Verse 19: And ye shall teach them unto your children ‘to speak of them.’ for the term v’shinantom [mentioned there]³⁴⁰Above, 6:7. means only that he shall “tell” them the commandments, and here [he added that the obligation extends] until they teach the words of Torah [to their children] and they understand them and their reasons [well enough] to discuss them with you at all times. So also he added here as the days of the heavens above the earth³³⁷Verse 21. which means “for all generations,” or it may refer to the first heaven and earth, and the days of old.³⁴¹See Vol. II, p. 341, Note 23. The student learned [in the mysteries of the Cabala] will understand.

ושמתם את דברי אלה על לבבכם, to understand them through intensive study;