Positive commandment · Mitzvat Aseh #5 of 613
To pray
לְהִתְפַּלַּל לוֹ
The verse · Shemot 23:25
וַעֲבַדְתֶּם אֵת ה׳ אֱלֹהֵיכֶם וּבֵרַךְ אֶת־לַחְמְךָ וְאֶת־מֵימֶיךָ וַהֲסִרֹתִי מַחֲלָה מִקִּרְבֶּךָ
“And you shall serve the Lord your God, and he shall bless thy bread, and thy water; and I will take sickness away from the midst of thee.”
The Rambam’s words
To pray, as [Exodus 23:25] states: "And you shall serve G-d, your Lord." This service is prayer.
לְהִתְפַּלַּל לוֹ, שֶׁנֶּאֱמָר: "וַעֲבַדְתֶּם, אֵת ה' אֱלֹהֵיכֶם" (שמות כג, כה) – עֲבוֹדָה זוֹ תְּפִלָּה.
Who & when
“And this commandment is practiced in all places and at all times by males and females.”
Where in the Mishneh Torah
Hilchot Prayer and the Priestly Blessing הלכות תפילה וברכת כהנים