Midrash sa Mga Awit 119:164: Midrash Tanchuma, Midrash Tehillim, Midrash Tanchuma Buber & Bamidbar Rabbah

You find that not all the eighteen benedictions (of the Amidah) recited each day are in praise of the Holy One, blessed be He. In fact, only the first three and the final three are in praise of Him, while the twelve intervening prayers allude to human needs. It is for this reason that we do not say the eighteen benedictions on the Sabbath.³On Sabbaths and holy dayss the thirteen intervening blessings are omitted lest the holiness of the day be marred by references to mundane affairs; a single benediction describing the characteristic feature of the day is inserted, in their place. For, if it should happen that a loved one was ill at home at the time of praying, the worshipper would be reminded of it while reciting the prayer “Who healeth the ills of His people” and would become depressed. Inasmuch as the Sabbath was given to Israel for sanctification, for joy and rest and not for sorrow, one must recite the first three blessings and the final three blessings (of the Amidah) and replace the intervening ones with the prayer of Rest. Hence, David proclaimed: Seven times a day do I praise Thee, because of Thy righteous ordinances (Ps. 119:164). The word seven in this verse refers to the seven benedictions recited on the Sabbath. What other day could this verse refer to, if not the day of rest, which is unlike any other? For it is said: Remember the Sabbath day and keep it holy (Exod. 20:8)—in every respect, even from in the pursuit of thy business and speaking thereof (Isa. 58:13).

Another interpretation of “But his delight is in the Torah of God” (Psalms 1:2) – anyone who toils in the Torah, the Holy One, blessed be He, fulfils his desires. Rabbi Eliezer said, “The Israelites said, before the Holy One, blessed be He, “Master of the Universe, we want to exert ourselves in Torah [study], day and night, but we have no free time.” The Holy One, blessed be He, said to them, “Perform the commandment of tefillin [i.e., the donning of phylacteries], and I will consider you as if you have exerted yourselves in Torah [study] day and night.”” Rabbi Yochanan said [that this can be derived] from that which is said, “And this shall serve you as a sign on your hand and as a reminder on your forehead – in order that God’s Torah should be in your mouth” (Exodus 13:9); [that is to say: if you wear your phylacteries, I will consider it as if the words of Torah had been in your mouth]. Rabbi Yehoshua said, “That which Rabbi Eliezer said only applies [during the day, when we are commanded to wear phylacteries, but] excludes the nights, since the commandment of phylacteries is only fulfilled during the day, as it said, “And you shall guard this statute at its set time from day to day” (Exodus 13:10) [from which we learn that the commandment of phylacteries, which was mentioned in the previous verse, applies only during the day]. Rabbi Eliezer replied to him [and asked – alluding to Psalms 1:2], “So what [commandment] do you observe [in order that you should be considered to have] meditated upon his Torah day and night?” Rabbi Yehoshua said to him, “That would be the recitation of the Shema. If a person recites it in the morning and the evening, the Holy One, blessed be He, considers it as if he had exerted himself in Torah [study] in the day and the night.” Bar Kapara said, anybody who reads [the first] two paragraphs [of the Shema], in the morning and the evening, fulfills the [precept] of “and on his Torah he meditates day and night” (Psalms 1:2). Rabbi Berechia said, even the Biblical forefathers established [fixed times] for learning – they would sit [and learn] in the part of the day that [in the winter] is taken over into the night; and they would sit [and learn] in the part of the night that [in the summer] is taken over into the day. They asked Rabbi Yehoshua whether a person is permitted to learn Greek wisdom. He told them, go out and find an hour that is neither day nor night, and [at that time only] you are permitted; since it is said, “And you shall meditate upon it day and night” (Joshua 1:8).” He turned around and said to them, “One shouldn’t teach one’s child Greek wisdom, nor even a trade, such that he shouldn’t cease from [studying] words of Torah, as it is said, “Choose life” (Deuteronomy 30:19) [as if to say, studying Torah, rather than pursuing a livelihood will give you life].” We learned that in the morning, one makes two blessings before [the Shema] and one [blessing] afterwards; and that in the evening, one makes two blessings before [the Shema] and two [blessings] afterwards; so that your meditation upon it in the day and night should be equal [and since the third paragraph of the Shema doesn’t have the same standing at nighttime as it does in the day, we instituted an extra blessing for the night, so that the same number of paragraphs would be recited with full weight in the morning and in the night]; “You should meditate upon it day and night” (Joshua 1:8). Rabbi Yossi says [that the three blessings in the morning, and the four in the evening were established] in virtue of [the verse], “I praise you seven times each day [for the justness of your laws]” (Psalms 119:164). Rabbi Yossi bar Avin said, in the name of Rabbi Yehoshua, anyone who embodies [the verse] “I praise you seven times each day,” is considered as if he meditated upon [the Torah] day and night.

"To the conductor on the eighth. This is what is stated (Psalms 119:164): Seven times a day I praise You. Rabbi Yehoshua ben Levi said these are the seven commandments mentioned in the recitation of Shema. [They are]: creation, love, [recitation of] Shema, speaking truth, [affirmation of God as] Redeemer, and [the commandments] concerning tzitzit and adding on to the sukkah of peace. Rabbi Avin in the name of Rabbi Nechemia said [these are] the seven commandments that a person does every day: [recitation of] Shema twice a day, praying three times a day, eating and blessing [before and after], and Rabbi Meir used to say: "Beloved is circumcision, for the Holy One, blessed be He, swore to Abraham that anyone who is circumcised will not descend to Gehenna, as it is said (Genesis 17:14), 'But the uncircumcised male whose foreskin has not been circumcised, that person shall be cut off from his people; he has broken My covenant.' And who goes down there? What is written after that? (Genesis 15:19-21) 'The Kenite, the Kenizzite, and the Kadmonite.'" And so Ezekiel says (Ezekiel 32:19), "Go down and lie with the uncircumcised," and Isaiah says (Isaiah 5:14), "Therefore, Sheol has enlarged its appetite and opened its mouth beyond measure." This is for those who do not have the covenant of circumcision. And where is the term "chok" (statute) mentioned? As it says (Psalms 105:10), "He established it for Jacob as a statute." But for the heretics and sinners of Israel who deny God, they are afflicted with uncircumcision and fall into Gehenna, as it says (Isaiah 9:20), "He has stretched out His hand against them and smitten them." This is because all the commandments that we have are not meant to be scrutinized meticulously, except for the commandment of circumcision and the empty words of the mouths of schoolchildren that have no sin, as it says (Jeremiah 33:25), "If not for My covenant, I would not have appointed the statutes of heaven and earth." For when a person enters the synagogue, he wraps himself in tzitzit and puts on tefillin on his head and arm, and four tzitzit surround him and guard his four corners. And when he enters the bathhouse, he looks at himself and says, "I am now naked of mitzvot (commandments)." And when he looks at the circumcision, which is equivalent to all the commandments, his mind is calmed. When David saw this, he composed a psalm on it, saying, "For the leader, on the eighth [day], a psalm, a song for the dedication of the Temple, of David. (This passage appears to be an addition from some copyist, as it is not the language of the Midrashim, as is known).