Positive commandment · Mitzvat Aseh #2 of 613
To unify Him
לְיַחֲדוֹ
The verse · Devarim 6:4
שְׁמַע יִשְׂרָאֵל ה׳ אֱלֹהֵינוּ ה׳ אֶחָד
“Hear, O Yisra᾽el: The Lord our God; the Lord is one.”
The Rambam’s words
To unify Him, as [Deuteronomy 6:4] states: "G-d is our Lord, G-d is one."
לְיַחֲדוֹ, שֶׁנֶּאֱמָר: "ה' אֱלֹהֵינוּ, ה' אֶחָד" (דברים ו, ד).
Why · Sefer HaChinuch #417
Unity of Hashem
“The root of this commandment is well-known, as it is the foundation of the faith of all people in the world and it is the strong pillar that every intelligent person relies upon.”
Who & when
“And this commandment is practiced in every place and at all times by males and females.”
Where in the Mishneh Torah
Hilchot Foundations of the Torah הלכות יסודי התורה