Еврейская мысль к Дварим 6:6

Let one learn from what G-d has commanded a king (of Israel) in saying: "And it will be, when he sits upon his royal throne, that he shall write for himself this Torah on a scroll...And it shall be with him always, and he shall read it all the days of his life [so that he may learn to fear the L-ord, his G-d, to keep all the words of this Torah and these statutes, to do them]" (Devarim 17:18), and "This book of the Torah shall not leave your mouth; you shall meditate therein day and night [in order that you observe to do all that is written in it, for then will you succeed in all your ways and then will you prosper]" (Yehoshua 1:8). And also (to every Jew in the Shema): "And these words, which I command you this day, shall be on your heart" (Devarim 6:6), and "you shall bind them for a sign upon your hand, and they shall be Totafos between your eyes" (Devarim 6:8). And He reinforced the matter in the chapter of Tzitzit in saying: "this shall be Tzitzit for you, and when you see it, you will remember all the commandments of the L-ord to perform them, and you shall not wander after your hearts and after your eyes after which you go astray" (Bamidbar 15:39), and then "So that you shall remember and perform all My commandments and you shall be holy to your G-d" (Bamidbar 15:40).

When they counted the commandments, they said: "we will not count in the negative commandments because merely refraining from them is their performance and the fulfillment of their obligation. Such service of G-d seemed too insignificant in their eyes, and their service seemed little to them due to their desire and longing for reaching the favor of G-d. Therefore they sought positive commandments of the limbs for individuals which apply at all times, places, and circumstances. They did not find any precepts that fits this except reading the torah and studying the commandments, as the verse says: "These words, which I command you this day, shall be in your heart; And you shall teach them diligently unto your children, and speak of them.." (Devarim 6:6). And the prophet (Moshe) exhorted on this a second time in saying: "You shall teach them to your sons, speaking of them, when you sit in your house and when you walk on the way and when you lie down and when you rise up" (Devarim 11:19).

Afterwards, He moved on to exhort on the duties of the heart, in saying: "And these words, which I command you this day, shall be on your heart", which means to cleave them to your heart, and believe them in your inner being.