In a number of contexts in Parashat Ekeb, the Torah instructs that we must serve G-d with all our heart (e.g. “U’l’obdo Be’chol Lebabchem” – Debarim 11:13). The Rambam maintains that this refers to the Biblical obligation of prayer. As the Gemara explains in Masechet Ta’anit, the way we serve G-d with our hearts is by turning to G-d in prayer. Explaining the reason for this Misva, the Sefer Ha’hinuch writes that prayer is the key to accessing G-d’s blessings. By turning to G-d, who has the unlimited capability to provide us with all our needs, and requesting those needs, we are able to obtain them, because Hashem responds to all those who call to Him with sincerity. Secondly, the Sefer Ha’hinuch adds, Tefila (prayer) enhances our awareness that Hashem is the master over the universe, the only Being who knows what we need, and who has unlimited ability to provide us with what we need, with nothing whatsoever that can ever prevent Him from giving us what He wishes to give us. This is a second purpose of prayer – to reinforce this belief in, and awareness of, G-d’s boundless control over the world. The Rambam writes that the Biblical obligation of prayer requires praying just once every day; the requirement to pray three times a day at specific times was enacted by the Sages. The Ramban challenges the Rambam’s position, questioning how the Rambam determined that the Biblical obligation requires praying each day. After all, since the Torah did not specify any particular time for prayer, we have no basis on which to determine whether the obligation is to pray once a day, once a week, once a month, once a year, or even once a lifetime. The Ramban therefore advances a different position, claiming that there is no Biblical obligation to pray each day. In the Ramban’s view, the Torah obligation requires praying only during an “Et Sara” – a time of crisis, when a person faces danger and needs help. Under such circumstances, one must pray on the level of Torah obligation, but otherwise, according to the Ramban, there is no Biblical requirement to pray. As mentioned, the Rambam concedes that the requirement to pray three times a day at specific times was enacted by the Sages; the Torah obligation requires praying only once at any point during the day. This is why the Sages formulated a brief prayer for one to recite when he finds himself in dangerous situation which does not allow him to recite the complete Amida prayer, as the Gemara discusses in Masechet Berachot. Since the fixed prayer is required only by force of Rabbinic enactment, the Rabbis suspended this requirement in situations of danger, and instituted a briefer prayer for the person to recite. The Talmud teaches that the three daily prayers – Shaharit, Minha and Arbit – correspond to the sacrifices offered each day in the Bet Ha’mikdash. The morning Shaharit prayer corresponds to the morning Tamid sacrifice; the afternoon Minha prayer corresponds to the afternoon Tamid sacrifice; and the evening Arbit prayer corresponds to the offering of the portions of sacrifices which were unable to be placed on the altar during the day, and were thus placed on the altar during the night. Since it was not always necessary to place these portions on the altar at night, the Arbit prayer, fundamentally, is optional, and not obligatory like the other two prayers. Practically speaking, the Jewish nation has accepted upon itself the Arbit prayer as an obligatory prayer, such that it is now obligatory like Shaharit and Arbit. On Shabbat, holidays and Rosh Hodesh, when a Musaf sacrifice would be offered in the Bet Ha’mikdash, we recite Musaf to commemorate that sacrifice. And on Yom Kippur we add a fifth prayer – Ne’ila. The text of our prayer service was composed by Ezra and his court. The first three Berachot express Shebah – praise to Hashem – whereas the next thirteen Berachot of the weekday Amida contain the requests that we present to G-d. The final three Berachot express Hoda’a – gratitude.