An impure Kohen, following immersion, must wait until after sundown before returning to service

This mitzvah establishes that purification from impurity occurs in two stages: immersion in a mikveh and the passage of sunset (הערב שמש). A kohen who immerses cannot immediately resume Temple service but must wait until nightfall, when his status changes from tevul yom (immersed that day) to fully pure.

Rambam codifies that a tevul yom kohen is still barred from avodah, though his impurity is less severe than before immersion. Sefer HaChinuch explains that this teaches discipline and reinforces the principle that holiness demands patience and complete readiness. Partial purification is insufficient for engaging in Hashem’s service.

The Talmud illustrates cases where kohanim who entered prematurely were disqualified, showing how halachah safeguards the sanctity of the Mikdash. This mitzvah emphasizes that the service must be performed in a state of shalem (wholeness), not halfway measures.

Commentary & Classical Explanation:

• Rambam (Hilchot Bi’at HaMikdash 1:10–12): Rules that a tevul yom kohen cannot serve until nightfall, for full purity requires both immersion and the setting of the sun.
• Sefer HaChinuch (Mitzvah 365): Explains that the delay teaches reverence and that true readiness demands patience.
• Rashi (Lev. 21:6): Notes that kohanim must remain holy, avoiding any service until they are completely purified.
• Talmud (Zevachim 17b; Berachot 2b): Discusses the principle of ha’arev shemesh and its significance in Temple service.
• Ramban: Adds that waiting until nightfall symbolizes the transition from impurity to full renewal, marking a spiritual rebirth.