Mitzvah 433: The commandment of prayer

The commandment of prayer: To serve God, may He be blessed, as it is stated (Deuteronomy 10:20), “and you shall serve Him.” And this commandment was repeated several times, as it is stated (Exodus 23:25), “And you shall serve the Lord, your God”; and in another place, it states (Deuteronomy 11:13), “and to serve Him with all of your hearts.” And Rambam, may his memory be blessed, wrote (Sefer HaMitzvot, Positive Commandments 5), “Even though this commandment is from the general commandments” - meaning to say that it includes all of the Torah, since the service of God includes all of the commandments - “there is also a specific [commandment] within it, and that is that God commanded us to pray to Him. And it is as they said in Sifrei Devarim 41:25, ‘“To serve Him with all of your hearts” - What is the service that is in the heart? That is prayer.’ And in the teaching of Rabbi Eliezer the son of Rabbi Yose HaGalili they said, ‘From where [do we know] that the essence of prayer is among the commandments? From here, “The Lord, your God, shall you fear, and you shall serve Him.”’”

Sefer HaChinukh cites Deuteronomy 10:20.

and you shall serve Him.

A corresponding passage could not be identified safely in this source record.

And this commandment is practiced in all places and at all times by males and females. And one who transgresses it and [goes for] a day and a night without prayer at all has violated this commandment according to the opinion of Rambam, may his memory be blessed. And one who is in difficulty and does not call to God to save him has violated this commandment, according to the opinion of Ramban, may his memory be blessed. And his punishment is very great as he is like one removes the providence of God from upon him.

• Exodus 23:25
• Deuteronomy 11:13
• Berakhot 21a
• Berakhot 31a
• Berakhot 27b