ורחצו אהרן ובניו ממנו את ידיהם ואת רגליהם. היה מקדש רגליו וידיו בבת אחת, ושנינו בזבחים כיצד קדוש מניח ידו הימנית על גבי רגלו הימנית וידו השמאלית על רגלו השמאלית ומקדש. ורחצו אהרן ובניו ממנו את ידיהם ואת רגליהם, “and Aaron and his sons shall wash their hands and their feet from this basin and the water therein.” The priest would wash his hands and feet at the same time, as has been explained in Zevachim 19. He would place his right hand on top of his right foot and his left hand on top of his left foot and would wash them.
וע"ד הפשט טעם רחיצת הידים מטכסיסי המלכות כי כן דרך המשרתים המתקרבים אל שלחן המלך לרחוץ ידיהם תחלה מפני שהידים עסקניות הן, ורחיצת הרגלים לפי שהיו משרתים יחפים. According to the plain meaning of our text, the need for performing this washing (assuming the priests had not entered the holy precincts with dirty hands or feet) was that it was an accepted ceremony before facing Royalty. Any of the king’s attendants who served food at his table had to wash his hands immediately prior to serving the food, seeing that hands are by nature busy with many activities of which the owner is often even unaware. The reason the priests also had to wash their feet immediately before performing sacrificial service was because they were barefoot (Jerusalem Talmud Shekalim 5,1).
וע"ד הקבלה טעם רחיצת הידים והרגלים לרמוז על עשר ספירות שכן ראשית האדם עשרה בהגביהו ידיו למעלה וסופו עשרה, והוא הטעם שתקנו לנו רז"ל נטילת ידים בתפלה ולשון נטילה ירמוז לזה שהוא לשון הגבהה כלשון (תהילים קל״ד:ב׳) שאו ידיכם קדש וזהו (שם קיט) ואשא כפי אל מצותיך אשר אהבתי וגו'. ולכך תרגם אונקלוס מלת ורחצו לשון קדושה שאמר ויקדשון ולא תרגם ויסחון כמשפטו בשאר המקומות לרמוז כי הכהן העובד מתלבש ומתקדש בקדושת י' ספירות, ויש בצורת האדם דוגמא להם בעשר אצבעות הידים וברית הפה בינתים וכן עשר אצבעות רגלים וברית מילה בינתים. A Kabbalistic approach: the washing of the ten fingers and ten toes was an allusion to the ten emanations which enabled the physical universe to be created out of a totally abstract domain. When man raises his hands above his head he raises ten fingers, i.e. alludes to these ten emanations. By standing on the ground with his ten toes he demonstrates that his beginning and end (in our parlance “top to bottom”) is all a reminder of these ten emanations. This is also the reason that the sages decreed that prior to praying one ought to wash one’s hands (Berachot 15). The expression נטילת ידים for “washing one’s hands,” [as opposed to רחיצת ידים] is an allusion to Psalms 134,2 שאו ידיכם קדש, “elevate, raise your hands (before) performing something sacred and proceed to bless the Lord.” A similar expression to the word שאו is found Psalms 119,48 where the psalmist says: “I raise my hands (elevate) towards Your commandments.” This is why Onkelos translates the word ורחצו, “they shall wash,” as ויקדשון, “they shall sanctify.” Elsewhere Onkelos translates the word ורחצו as: ויסחון such as in Genesis 18,4 where Avraham asks his guests to wash their feet. The Torah hints that the priest who performs service in the Tabernacle/Temple “clothes” himself in the sanctity of the ten emanations by the act of washing his hands and feet from the basin. Nachmanides views the covenant with G’d which was both oral (mouth) and on man’s flesh (circumcision), as symbolically interposed between the ten fingers of the two hands and the ten toes of the two feet respectively.