שמות, פרק כ״ט, פסוק ל״ה

The consecration of the priests for service in the Tabernacle was not a simple, one-time event. It required a precise and continuous process to firmly establish their new role. Every detail of the ordination instructions was absolutely essential. If Moses missed even a single action from the prescribed order of sacrifices and ceremonies, the entire ordination would be void, rendering any future service by the priests invalid [רש״י, מזרחי, רש״ר הירש].

Moses was tasked with carrying out this ordination because he served as the supreme representative of the entire nation, appointing the priests on behalf of the people [רש״ר הירש]. He was expected to perform this duty not merely as a formal requirement, but with a willing heart and genuine joy when appointing his brother to this high position [הכתב והקבלה].

The instructions also established a direct comparison between Aaron and his sons regarding their sacred garments. Just as the High Priest wore a belt woven from a specific mixture of wool and linen, the belts worn by Aaron's sons were made of this exact same mixture [תורה תמימה].

The ordination process lasted for a full week. This did not mean spreading the steps of the ceremony out over seven days. Rather, Moses was required to repeat the complete sequence of sacrifices and rituals, from start to finish, every single day for seven consecutive days [רש״י, מזרחי, גור אריה].

Historically, this week of dedication took place just before the start of the month of Nissan. Throughout these seven days, Moses himself served as the acting priest. Each morning, he would set up the Tabernacle and offer the daily sacrifices, and each evening, he would dismantle the structure. It was only on the eighth day, the first of Nissan, that the Tabernacle was erected permanently. From that moment onward, the sacred duties were transferred exclusively into the hands of Aaron and his sons [רשב״ם, ביאור יש״ר].