This mitzvah commands the Jewish people to sanctify Shabbos through words, marking its entrance with Kiddush and its departure with Havdalah. The Torah instructs, “זָכוֹר אֶת יוֹם הַשַּׁבָּת לְקַדְּשׁוֹ”—“Remember the day of Shabbos to sanctify it.” Chazal explain that this remembrance is fulfilled through verbal sanctification, declaring the holiness of the day when it enters and distinguishing it when it departs.

Kiddush affirms the sanctity of Shabbos, testifying to Creation and the covenant between Hashem and Israel. Havdalah, in turn, marks the transition from sacred time back into the weekday world, reminding the Jew that the holiness of Shabbos must continue to influence the days that follow. Together, these declarations transform time itself into an arena of awareness, gratitude, and spiritual consciousness.

Rambam

• Sefer HaMitzvos, Aseh 155:
  The mitzvah of Zachor is fulfilled through verbal sanctification of Shabbos.
• Hilchos Shabbos 29:1:
  One must mention the sanctity of Shabbos at its entrance and at its departure.
• Kiddush and Havdalah are expressions of remembering and distinguishing sacred time.

Sefer HaChinuch

• Mitzvah 31:
  The mitzvah reinforces belief in Creation and the Exodus.
• Verbal sanctification engraves the holiness of Shabbos into the heart and mind.

Rashi

• On “זָכוֹר אֶת יוֹם הַשַּׁבָּת” (Shemos 20:8):
  One must remember Shabbos through words, sanctifying it upon its arrival.

Ramban

• Shabbos remembrance affirms both Creation and redemption from Egypt.
• Sanctifying the day verbally makes faith a lived, conscious reality.

Talmud

• Pesachim 106a:
  Kiddush is recited over wine to honor and sanctify the day.
• Berachos 33a:
  Havdalah distinguishes between sacred and ordinary time.
• Shabbos 113a:
  Honoring Shabbos through speech reflects its sanctity.

Midrash & Chazal

• Mechilta:
  “Remember it with wine at its entrance.”
• Kiddush transforms the moment of transition into an act of sanctification.

Acharonim & Modern Torah Giants

• Rav Hirsch
  Kiddush declares that time belongs to Hashem, not to human control.
• Netziv
  Havdalah teaches that holiness must flow into the weekday.
• Rav Kook
  The transition from Shabbos to weekday reflects the movement from spiritual perfection into practical life.

Chassidic & Mussar Classics

• Baal Shem Tov
  Words of Kiddush draw holiness into the physical world.
• Tanya
  Sanctifying Shabbos with speech reveals the soul’s connection to Divine time.
• Sfas Emes
  Kiddush awakens the inner holiness already present in the day.
• Ramchal
  Sanctified speech elevates time itself into a vehicle for spiritual growth.

Contrast with Mitzvah 88 — Not to Do Melachah on Shabbos

• Mitzvah 88 prohibits creative labor.
• Mitzvah 91 sanctifies the day verbally.
• One defines the boundary of Shabbos; the other defines its identity.

Parallel to Mitzvah 87 — To Rest on Shabbos

• Mitzvah 87: Positive state of rest.
• Mitzvah 91: Verbal sanctification of the day.
• Rest shapes the experience; Kiddush gives it expression.

Midrashic Insight — The First Havdalah Fire

• The Talmud (Pesachim 54a; Avodah Zarah 8a) teaches that when the first Shabbos ended, Adam experienced darkness for the first time. Until then, he had lived in a world illuminated by a special primordial light. When night fell, he feared that the world was returning to chaos because of his sin. Hashem then granted him wisdom, and Adam struck two stones together, producing the first human-made fire. In gratitude, he recited the blessing, “Borei me’orei ha’eish”—the blessing over fire that we recite every Motzaei Shabbos. This teaching explains why Havdalah includes a multi-wick flame, commemorating the first light Adam created at the close of the first Shabbos (Shulchan Aruch, O.C. 298:2). Chazal add that we look at our fingernails during the blessing because they are remnants of the luminous covering that once clothed Adam before his sin (Bereishis Rabbah 12:6; Berachos 53b).