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).
However, according to Ramban (Glosses to Rambam’s Sefer Ha-mitzvot), there is no biblical obligation to pray every day, because, in his opinion, the extrapolation from the verses that Rambam mentions is not a bona fide exegesis, but merely an asmakhta (reference). Rather, the Men of the Great Assembly instituted daily prayers but based their enactment on biblical verses. Ramban maintains that only in times of trouble is there a biblical commandment to pray to God, as we learn from the mitzva of the trumpets (ĥatzotzrot), where it says (Bamidbar 10:9), “When you go to war against an enemy that attacks you in your land, you shall sound a teru’a (short blasts) on the trumpets. You will then be recalled before the Lord your God and will be delivered from your enemies.”
Thus, according to all opinions, there is a biblical obligation to pray in times of trouble. Therefore, anyone who finds herself or her friend in a state of crisis is required to add a special request for assistance in her prayer, since it is a biblical commandment to petition God to save her from that trouble. It is certainly a mitzva to pray communally when the public or the nation is in danger. The Sages even instituted fast days for that purpose.
Next, we will continue to study the order of the prayer service instituted by the Men of the Great Assembly, and in chapter 2 we will learn which specific prayers are incumbent on women.