Halakhah su Deuteronomio 11:13

The recitation of Shema includes three paragraphs. The first is “Shema” (“Listen”; Devarim 6:4-9), in which we accept the yoke of heaven and which discusses God’s unity and our love for Him. The second is “Ve-haya im Shamo’a” (“And if you follow”; Devarim 11:13-21), which contains the acceptance of the yoke of the mitzvot. The third is “Va-yomer” (“And He said”; Bamidbar 15:37-41), within which there is a command to remember the mitzvot via the mitzva of tzitzit, and at the end of which the Exodus from Egypt is mentioned.

The Rishonim disagree about whether there is a Torah commandment to pray every day. According to Rambam (Sefer Ha-mitzvot, mitzva 5), there is a biblical commandment to pray daily, as the Torah states (Shemot 23:25), “Serve God your Lord,” and (Devarim 6:13) “Revere the Lord your God and serve Him.” Although these verses contain a general commandment to serve God, they also include a specific commandment to pray. The Sages interpreted “service” (avoda) to mean worship through prayer, as it is written:  “Love God your Lord and serve Him with all your heart” (Devarim 11:13), and they explained (Ta’anit 2a), “What is serving with the heart? It must mean prayer.” By praying daily, one fulfills her biblical obligation to pray. To fulfill one’s obligation, one must begin with praise to God, then petition God for her needs, and conclude by thanking God for the good He has bestowed upon her. The Torah does not specify how long one’s prayers must be. Therefore, some shorten their prayers and others lengthen them, yet they all fulfill their biblical obligation (MT, Laws of Prayer 1:2-3). Later, the Men of the Great Assembly formulated a set prayer text, as will be explained below (section 6).

That is that we are commanded to serve Him. And this command is repeated several times: His saying, "And you shall serve the Lord, your God" (Exodus 23:25); and His saying, "and you shall serve Him" (Deuteronomy 13:5). And although this command is from the inclusive commands - as we explained in Principle Four (Sefer HaMitzvot, Shorashim 4) - it nevertheless has specificity, since it is the command to pray. The language of the Sifrei is, "'And to serve Him' (Deuteronomy 11:13) - that is prayer." And they also said, "'And to serve Him' - that is [Torah] study." And in the Mishnah of Rabbi Eliezer, the son of Rabbi Yose HaGelili, they said, "From where [do we know that] the essence of prayer is a commandment? From here - 'You shall fear the Lord, your God, and you shall serve Him' (Deuteronomy 6:13)." And they said, "Serve Him through His Torah; serve Him in His Temple." This means, direct [yourself] towards it, to pray [towards] there, as Shlomo, peace be upon him, explained. (See Parashat Mishpatim: Mishneh Torah, Prayer and the Priestly Blessing 1.)