Halakhah su Deuteronomio 6:5

It is a positive commandment to love God, may He be blessed, with all one's heart, and all one's soul, and all one's might. As it is said (Deuteronomy 6:5): "You shall love the LORD your God with all your heart and with all your soul and with all your might." The way to love Him is to meditate on His acts until one contemplates them to the degree to which he is able - when the heart is aflame with the love of Him. This is the love which is incumbent upon us. One should direct all of his thoughts toward the love of God, may He be blessed. A person can only love the Holy One, blessed be He from the knowledge with which he knows Him, so in proportion to that knowledge will be the love: if [the knowledge is] small, [the love will be] small; if great, great. Therefore, a person needs to focus himself on understanding and comprehending, through wisdom and known philosophies, the honor of his Master, in proportion to the ability which he has to understand and attain. This is one of the commandments which a person is obligated in at all times, at every moment. Included in this commandment is [the requirement] to bring people close to His service, may He be blessed, and to love Him for what he has created, as our forefather Avraham, peace be upon him, did, as it is said (Genesis 12:5): "And the souls which he created in Haran." Because of this, the Holy One, blessed be He, called Avraham His beloved, as it is said (Isaiah 41:8): "Avraham my beloved."

(Zayin) There is still more. This [required] study must be from love, such that he not use this trait for anything else at all, ‘but rather his desire is for the Torah of the Lord.’ And these are the words of the Midrash Tanchuma, Noach 3:4-7:
The Israelites did not accept the Torah until the Holy One, blessed be He, arched the mountain over them like a vessel, etc. If you should say it was because of the Written Law, isn’t it true that as soon as He said to them, “Will you accept the Torah,” they all responded (Exod. 24:7), “We will do and hear?” … But rather He said this to them because of the Oral Law, etc. And its jealousy is as harsh as Sheol.²⁸The pit, usually a reference to the nether-world. One does not study the Oral Law unless he loves the Holy One, blessed be He, with all his heart, etc., as it is stated (Deut. 6:5), “And you shall love, etc.” Whence do you learn that this word, “love,” refers only to studying the [Oral Law]? Observe what is written after this (Deut. 6:6): “And these words which I command you this day shall be upon your heart.” And what study is upon the heart? Scripture (Deut. 6:7) states [immediately thereafter], “And you shall review it to your children.” [Hence] this is the study that requires review (i.e. the Oral Law). We learn from these verses that the first part of the Shema (Deut. 6:4-9) does not mention a reward given in this world, while the second part does: “And if you shall hearken diligently, etc., I will give the rain of your land in its season” (Deut. 11:13). This reward is given to those who perform the commandments even though they neglect study [of the Oral Law], etc. As anyone who loves material riches and earthly pleasures is incapable of studying the Oral Law. [This is because] there is considerable anguish and sleeplessness in (store for him who studies) it; one wastes and neglects himself on its account. Therefore its reward is in the hereafter, as it is said (Isaiah 9:1), “The people that walk in darkness have seen a great light,” etc. Therefore the Holy One, blessed be He, established two academies (at Sura and Pumbeditha) for the Israelites where they studied the Torah day and night and where they assembled from all parts of the world twice each year – in the months of Adar and Elul. They came together to “battle” the problems encountered in the Torah until they had resolved them and reached a definitive decision concerning the law. [See there, as it is lengthy.]
And [the Rabbis] said in the Midrash that the Holy One, blessed be He, forced us [to accept the Oral Law] by arching the mountain, such that the Torah would not be severed from us forever. As with a [woman] forced [to have sexual relations], it is written (Deut. 22:19), “he may not send her away all of his days.”²⁹See the next paragraph and note 34. Also the manna that they ate in the wilderness was [given] with this intention. As it is written in Maggid Mesharim of Beit Yosef (R. Yosef Karo), that the manna that the Israelites ate was necessary in order [for them] to receive the Torah without any choice. And these are the words in Yalkut Reuveni, Beshelach: [The angel named] Yafefiyah who is the one who rained down the manna upon Israel, is numerically equivalent (with the letters adding up to 197) to Katseh, who is the angelic minister of Torah; whereas they said (Num. 21:5), “and our souls are sick (katseh)” – to make known that they were sick and disgusted of the manna and of the Torah. See there. And this was forcing them to receive the Torah, as the manna was coming from the minister of the Torah, and it was the bread of mighty ones from which the ministering angels are sustained. [Hence] they no longer had any physical desire or inclination. Rather it was [therewith only] the love of the Torah and of the commandments that was implanted in their hearts. And this [love] remained for [future] generations among the enlightened ones about whom it is stated (Num. 19:14), “when a man dies in a tent.”³⁰ See Berakhot 63b.

The root of loving God is loving God with all your heart (Deut. 6:4). Our Creator commanded us to serve him with love,¹The term “love” is the preferred reading. that the love of our soul be bound up with His soul in joy and in His love and with a good heart. And the joy of this love is of such intensity and so overpowers the heart of those who love God, that even after many days of not being with his wife and having a great desire for her, in the hour that a man ejaculates he does not find it as satisfying as the intensity and power of loving²Ibid. God and finding joy in his Creator. And all the pleasures of playing with his children are as naught compared to the pleasures of the heart of the man who loves God with all his heart and soul and with all his might, i.e., with all his thoughts, about how to love God and how to make the public acquire merit and sanctify God’s name, and how to devote himself with love to the Creator,³Berakoth 61b. as did Phineas the priest who dedicated himself with love for his Creator to be zealous in His name. Let him not covet money in a situation where there is a Sanctification of God’s name if he resists taking money, as we find with Abraham, “that I will not take a thread or a shoe latchet” (Gen. 14:23). And so (it was) with Elisha who did not want to take money from Naaman. Let him not neglect the study of the Law because of pleasures, playing with his children or attachment to his wives. Also let him give up leisurely walks, meeting with women, sweet songs, in order that his heart may be whole in the joy of God, toiling and laboring in that which is the will of the Creator. He should take a lesson from one of flesh and blood. If he knew a matter to be the desire of a king, he would not yield nor rest until he fulfilled the will of the king, who is a worm like himself. He would be overjoyed that his deeds received the notice of the king and especially if it met with the will of the Creator who is eternal. Therefore must he labor all the more and seek how to fulfill the will of His commandments. He who serves out of love, occupies himself with Torah and commandments, goes in paths of proper wisdom and occupies himself with Torah and loves God with great love, not for any other reason, and not for fear of evil, nor for the purpose of inheriting the good. But he serves in truth, because the Holy One, blessed be He, is truth and in the end the good will come because of it.⁴Nedarim 62a. He must love the Creator with a great and strong love until he becomes sick because of his love, as the man who is love-sick for the affections of a woman and reels constantly because of his love, when he sits, rises, goes and comes, also when he eats and drinks. He neither sleeps nor slumbers because of this love. Greater than this should love of the Creator be in the hearts of those who love Him and they should be absorbed in it constantly,⁵Rosh ha-Shanah 4a. as we were commanded, “with all thy heart, with all thy soul …” (Deut. 6:4); and this is what Solomon in his wisdom said by the way of simile: “For I am love-sick” (Cant. 2:5). And this is a matter as clear as day and sun, for all who know that love of the Creator is not bound up with the heart of man until he is absorbed in it continuously, so as, for example, to forsake all else in the world outside of Him, as He commanded us “with all thy heart” (Deut. 6:4). This is impossible except through the apprehension of the mind. Therefore this is the truth, and the sum of it all is, that man must understand and study in the wisdoms and disciplines that make known to him his Master⁶Shabbath 75a. according to the intellectual ability that he possesses to understand, consider and comprehend.⁷Maimonides, Hilkhoth Teshuvah, 10:6. And the Creator, blessed be His name and exalted be His revered and awesome fame, commanded us to love and fear His name, as it is written “and thou shalt love the Lord thy God” (Deut. 6:4); and it is said, “thou shalt fear the Lord thy God” (Deut. 6:13). And which is the way in which to love Him and fear Him? In the hour that the individual comprehends the great and wondrous works of God, the Holy One, blessed be He, which are beyond assessment and limit, he immediately loves, praises, glorifies and yearns deeply to know that great, revered and awesome name.⁸Moses Maimonides, Book of the Divine Commandments, trans. Charles Chavel (2 Vols.; London: Soncino Press, 1940), I, 82, commandment 3. And thus did David say, “My soul thirsteth for God for the living God” (Ps. 42:3). And when he reflects upon these matters he will be startled, he will fear, and will tremble that he is a very small and lowly creature standing with poor and scanty knowledge before Him.⁹Maimonides, Hilkhoth Yesode Ha-Torah, 2:2, adds the words, “Who is omniscient,” (literally, “Whose knowledge is complete”). And so did David say, “When I behold Thy heavens the work of Thy fingers etc…. What is man that Thou art mindful of him” (Ps. 8:4).