שמות, פרק ל׳, פסוק כ׳

Before performing their sacred duties or stepping into the holy areas, the priests are commanded to wash their hands and feet. This act of purification is an absolute requirement, carrying severe consequences for those who neglect it. The obligation applies to two distinct locations: entering the inner sanctuary of the Tabernacle, and approaching the outer altar situated in the courtyard [רש״י, שפתי חכמים, ביאור יש״ר].

A central discussion arises regarding whether a priest must wash if he enters the sanctuary without the intention to perform a service. One perspective maintains that the requirement to wash applies strictly when a priest enters to do actual work, such as offering incense or sprinkling blood. If he enters merely to bow down, washing is not required [רש״י, הכתב והקבלה, משכיל לדוד, ברכת אשר, רלב״ג]. Conversely, another approach draws a sharp distinction between the two locations. Because priests frequently approach the outer altar for reasons other than service, washing is only mandated there when actual duties are performed. However, the inner sanctuary holds such immense holiness that any entry at all—even if just for maintenance or without a specific task—demands washing out of respect for the space [העמק דבר, קאסוטו, הכתב והקבלה בשם התוספות].

The physical act of washing must be done specifically with water [אבן עזרא, אבי עזר]. Furthermore, the priest must stand while washing, as this preparation is considered an integral part of the service itself [תורה תמימה]. The water used must be sanctified. While the primary instruction is to wash from the designated basin, water from other sacred vessels is also acceptable [רלב״ג, תורה תמימה]. Generally, a single washing in the morning covers all of the priest's duties for the entire day, provided he does not leave the Temple grounds or lose his focus [משכיל לדוד, תורה תמימה]. This strict requirement is not limited to major, atoning rituals; it is equally necessary for secondary tasks, such as burning certain fats on the altar [תורה תמימה].

Failing to wash before serving carries a penalty of death at the hands of Heaven. Additionally, any service performed by an unwashed priest is completely invalid, much like the service of a priest with a physical blemish [רלב״ג, תורה תמימה]. The instruction is framed as a warning to wash so that they do not die, rather than a direct threat that they will die if they do not wash. This phrasing reflects a general pattern where rules are taught through positive statements, from which the negative consequences are naturally understood [רש״י, שפתי חכמים]. Moreover, approaching God without washing demonstrates a profound lack of respect that warrants death. Since death by Heaven is often delayed rather than immediate, stating that they will die might incorrectly imply an instant punishment. Therefore, the instruction is framed as a promise: by washing, the priests will be saved from death [גור אריה].