This mitzvah defines the foundation of Jewish belief: Hashem is absolutely One — not composed of parts, not divided, not represented by multiple forces or beings. Nothing shares His essence or competes with His sovereignty. By commanding Jewish people to recite “Shema Yisrael,” the Torah teaches us to declare and internalize this unity daily — unifying the mind, heart, and world under Hashem’s singular truth.

Rambam

• Source: Yesodei HaTorah 1:7; Sefer HaMitzvos, Aseh 2. Rambam teaches that Hashem’s Oneness is not merely numerical but absolute — without division, composition, or multiplicity. Any belief in Divine “parts” is a denial of His true perfection. Rambam requires us to contemplate and know this unity intellectually until it becomes the center of our worldview.

Sefer HaChinuch

• Mitzvah 417. The Chinuch explains that the unity of Hashem is the foundation of all mitzvos. Since every command originates from the same Divine Will, fulfilling mitzvos expresses loyalty to the One Commander. He notes this mitzvah’s constant relevance — morning, night, and every conscious moment — because reality constantly reflects Hashem’s unity.

Rashi / Ramban / Ibn Ezra / Sforno / Abarbanel / Midrashim

• Rashi (Devarim 6:4) highlights: “ה' אֱלֹהֵינוּ” — now He is our G-d, but in the future He will be recognized as the One G-d over all humanity.
• Ramban stresses that unity means Hashem alone should be worshipped, because no separate force exists to compete for devotion.
• Ibn Ezra explains “אֶחָד” not as number but as the exclusive Source of all existence.
• Sforno notes that Divine unity guarantees perfect providence — since no external force interferes with His will.
• Abarbanel argues that unity ensures the coherence of truth: multiple ultimate authorities breed contradiction and chaos.
• Midrash teaches that the Shema is a declaration of spiritual allegiance — a coronation of Hashem in our inner world each day.

Talmud & Midrash

• Berachos 13b derives that kabbalas ol malchus Shamayim — accepting the yoke of Heaven — is fulfilled through Shema. The verse is not merely recited; it is a mental coronation of the King whose unity defines reality.
• The Sifri derives the mitzvah to recite Shema twice daily, ensuring that unity remains the anchor of consciousness during the transitions of day and night.

Kuzari, Maharal, and Other Rishonim

• Kuzari emphasizes that unity is experienced through relationship — Hashem Himself interacts with Am Yisrael directly, without intermediaries.
• Maharal explains that Divine unity means ultimate simplicity — no composition or dependency. Since multiplicity depends on parts, true perfection can only be One.
• Other Rishonim explain that His unity ensures that nature and history are organized and purposeful — flowing from one mind and one will.

Shulchan Aruch & Halacha

• Orach Chaim 60–63 codifies precise kavannah for the Shema, especially the word “אחד,” to mentally expand Hashem’s sovereignty over heaven, earth, and the four directions.
• Halacha requires covering one’s eyes during Shema to focus the mind — protecting unity from distraction and fragmentation.

Acharonim & Modern Torah Giants

• Chasam Sofer notes that intellectual unity creates inner peace; divided beliefs create inner conflict.
• Rav Hirsch teaches that unity of G-d produces unity of morality — one Divine source means objective ethics.
• Chazon Ish emphasizes that true bitachon rests on unity: if only Hashem rules, nothing else determines our fate.
• Rav Kook teaches that recognizing Hashem’s unity reveals the hidden unity within creation — everything becomes a vehicle for serving Him.

Chassidic & Mussar Classics

• Baal Shem Tov teaches that Divine unity permeates every event — even concealment reveals the One who hides.
• Tanya (Shaar HaYichud v’Ha’emunah) explains that Hashem continuously creates existence; nothing exists independently for even a moment.
• Sfas Emes writes that unity must penetrate the soul — aligning the heart’s desires with Hashem’s will.
• Ramchal says true piety means seeing Hashem as the only true power; unity becomes the lens for every decision.

Contrast with Mitzvah 2 — Not to believe in other gods

• Mitzvah 2 negates rivals
• Mitzvah 3 affirms unity

One uproots error; the other builds the truth.

Parallel to Mitzvah 1 — To know that He exists

• Existence → Who He is
• Unity → What He is

Both together define the Jewish concept of G-d.