The dedication of the Tabernacle is a momentous event marked by unique offerings that step outside the standard rules of temple service. During this ceremony, a specific sacrifice is completely consumed by fire, presenting a notable exception to the usual laws of offerings.
The primary approach among commentators is to identify this sacrifice as an outer sin offering, meaning its blood is applied to the outdoor altar. Ordinarily, the meat of an outer sin offering is eaten by the priests, while only inner sin offerings, whose blood is brought into the sanctuary itself, are burned outside the camp. Yet in this unusual instance, an outer sin offering is treated like an inner one, and its meat is burned [רש״י, ברכת אשר על התורה, שטיינזלץ]. This departure from standard practice is not a mistake but a specific, temporary ruling commanded directly by God [רש״י, בכור שור, משכיל לדוד]. Commentators explain that this special law applies to a broader category of dedication offerings used to initiate service. This group includes the initial seven days of training for the priests, their eighth day of actual service, the dedication of the Levites, the offerings brought during the time of Ezra, and even the future dedication sacrifices described in the book of Ezekiel [מזרחי, ריב״א, שפתי חכמים, חזקוני].
Beyond the formal divine command, there are practical reasons for burning the meat. The most immediate issue is the lack of eligible priests to eat it. Because this offering is brought to atone for Aaron and his sons to prepare them for their new roles, they are not permitted to eat their own sin offering. With no one qualified to consume the meat, burning it is the only option [רש ר הירש, פירושי רד צ הופמן]. This aligns with the broader rule that a priest's personal sacrifices, such as his meal offering or a specific bull brought by an anointed priest, are entirely consumed by fire and never eaten [פענח רזא].
There is also a profound spiritual meaning behind the total destruction of this offering. The animal brought is a calf, specifically intended to atone for the sin of the Golden Calf. Both the meat and the skin are burned together, which is unusual since the skin of a standard burnt offering is normally given to the priests. The purpose here is to completely erase any memory or remaining trace of that past sin. By leaving nothing behind, Aaron is thoroughly purified, free from any lingering stain or flaw [שפתי כהן]. Finally, regarding the physical destruction of the offering, Aaron does not necessarily carry out the burning with his own hands. Instead, he directs others to perform the task on his behalf [פירושי רד צ הופמן].