Deuteronomy 11:13

והיה אם שמע AND IT SHALL COME TO PASS IF YE WILL HEARKEN — The word והיה is to be connected with what is said above (v. 11): “it drinketh water of the rain of heaven”. שמע תשמעו lit: AND IT WILL COME TO PASS IF HEARKENING YE WILL HEARKEN — If you hearken to the old (if you hear again what you have already learnt, i.e. if you repeatedly study the old lessons), you will hearken to the new (you will the more easily gain new knowledge) (Sukkah 46b; cf. Rashi on Exodus 19:5). Similar is the meaning of אם שכח תשכח (Deuteronomy 8:19): If you have begun to forget, your end will be that you will forget all of it. So, too, is written in a certain Scroll: If thou forgettest Me one day, I will forget thee two days (cf. Sifrei Devarim 48:8; Jerusalem Talmud end of Berakhot). מצוה אתכם היום [MY COMMANDMENTS WHICH I] COMMAND YOU THIS DAY — This suggests that they should ever be to you as new commandments, as though you had heard them for the first time on that day (Sifrei Devarim 58). לאהבה את ה׳ TO LOVE THE LORD — This means that you should not say: Well, I will learn, but in order that I may become rich, in order that I may obtain the title Rabbi, in order that I may receive a prize, — but whatever you do, do it out of love for God (Sifrei Devarim 41:23), and ultimately the honour which you desire will certainly come (Nedarim 62a). ולעבדו בכל לבבכם AND TO SERVE HIM WITH ALL YOUR HEART — i.e. to serve Him with a service that is in the heart: that is prayer, for prayer is termed service (עבודה), as it is said, (Daniel 6:17) “Thy God whom thou servest continually”. But was there service (i.e. sacrificial service, the technical term for which is עבודה) in Babylon? But the term is used because he offered prayer there, as it is said, (Daniel 6:11) “Now his windows were open [in his upper chamber towards Jerusalem and he kneeled upon his knees three times a day and prayed]”. And so, too, it states in the case of David (Psalms 141:2): “Let my prayer be set forth as incense before Thee” (incense being part of the sacrificial service) (Sifrei Devarim 41:25-27). בכל לבבכם ובכל נפשכם [TO LOVE THE LORD] WITH ALL YOUR HEART AND WITH ALL YOUR SOUL — But has it not already admonished us to love God, by the words (6:5) “[Thou shall love the Lord thy God] with all thy heart and with all thy soul”? But that was an admonition addressed to each and every individual (“with all thy heart”), whilst here it is an admonition addressed to them as a community (“with all your heart”) (Sifrei Devarim 41:29).

וְהָיָ֗ה אִם־שָׁמֹ֤עַ תִּשְׁמְעוּ֙ אֶל־מִצְוֺתַ֔י אֲשֶׁ֧ר אָנֹכִ֛י מְצַוֶּ֥ה אֶתְכֶ֖ם הַיּ֑וֹם לְאַהֲבָ֞ה אֶת־יְהֹוָ֤ה אֱלֹֽהֵיכֶם֙ וּלְעׇבְד֔וֹ בְּכׇל־לְבַבְכֶ֖ם וּבְכׇל־נַפְשְׁכֶֽם׃

And it shall come to pass, if you hearken diligently to my commandments which I command you this day, to love the Lord your God, and to serve him with all your heart and with all your soul,