Preparing to serve in the Tabernacle required a profound physical and spiritual purification, marking a necessary transition from the mundane world into the sacred space. The primary approach among commentators is that this washing is rooted in the protocols of royalty and reverence. Just as a servant approaching the table of a mortal king must wash his hands because they are constantly active and touching various objects, the priests were required to cleanse themselves before God. Furthermore, the priests performed their sacred duties barefoot to ensure there was no barrier between them and the Tabernacle floor. Consequently, their feet naturally accumulated dirt and sweat. Honoring God's presence therefore demanded meticulous physical cleanliness [רמב״ן, רבנו בחיי, הטור הארוך, רלב״ג].
Beyond physical hygiene, this act held a deeper spiritual significance connected to the human form. The hands and feet represent the upper and lower extremities; when a person raises their hands, their entire body is encompassed between these points. The ten fingers and ten toes correspond to the ten Divine spheres, transforming the washing into an act of profound spiritual sanctification. Reflecting this elevated status, the Aramaic translation of Onkelos renders the act here as "sanctification" rather than ordinary washing [רמב״ן, רבנו בחיי, מיני תרגומא]. Drawing from this concept of holiness, the sages established the obligation to wash hands before prayer, as prayer serves as the modern equivalent of the sacrificial service [רמב״ן, הטור הארוך, תורה תמימה]. The traditional terminology for washing hands derives either from the specific vessel used, called a Natla [פרדס יוסף], or from the concept of elevating and uplifting the hands in holiness [רבנו בחיי]. Notably, Moses is not included in this eternal instruction because his role as a priest was only temporary during the inauguration period, whereas this directive was established for the regular, serving priests throughout the generations [אבן עזרא].
The procedure required the water to be poured directly from the basin. A priest could not simply dip and rinse his hands inside the basin itself, as doing so would invalidate the remaining water. The washing also had to be performed using a dedicated sacred vessel rather than a secular one [תורה תמימה, חזקוני]. To accommodate the service, the basin was designed with specific proportions, containing enough water to wash Aaron and his three sons simultaneously [רלב״ג, מלבי״ם], utilizing two separate faucets or pipes [אבן עזרא הקצר]. However, the essential Commandment was the act of washing from a vessel; the basin itself was merely a preparatory tool. This is evidenced by the Yom Kippur service, where the High Priest used a golden jug rather than the standard basin [רמב״ן].
The washing of the hands and feet had to be performed simultaneously rather than sequentially [אור החיים, רש״י, תורה תמימה, שפתי חכמים, משכיל לדוד]. This integrated action resolved a conceptual dilemma: a fundamental rule of holiness dictates that one must always ascend in sanctity and never descend. If the limbs were washed one after the other, it would create uncertainty regarding which should be prioritized. Washing them together entirely avoided this issue [גור אריה]. Practically, the priest would bend downward, placing his right hand on his right foot and his left hand on his left foot, rubbing them together as the water flowed over them [רש״י, רבנו בחיי, ברכת אשר]. The required measure for this cleansing extended up to the wrist joints for the hands, and up to the ankles for the feet [תורה תמימה]. While the sacrificial service strictly required the sanctification of both hands and feet—and would be invalid if the feet were left unwashed [מלבי״ם]—the act of eating the sacrificial meat required only the washing of the hands [פרדס יוסף].