The sudden tragedy of the deaths of Nadab and Abihu demands immense mental strength from Aaron and his remaining sons. In a moment of deep personal grief, they must set aside their private mourning in deference to the sanctity of their public role, continuing to represent holiness without a flaw. They are instructed not to leave the Tabernacle to mourn their dead. The primary approach among commentators is that this restriction applies specifically during active service in the sanctuary; a priest may not abandon his holy work, though he is permitted to leave for personal needs when not actively serving [תורה תמימה, ביאור ישר, מלבי״ם, פרדס יוסף, אדרת אליהו, ברכת אשר]. Furthermore, remaining inside the Tabernacle reflects the idea that Divine blessing and kindness rest only upon that which is modest and hidden from the eye [רקנאטי].
This instruction sparks a fascinating discussion regarding how the restriction applies to future generations. One approach maintains that the warning not to leave the sanctuary during service applies permanently to all priests. According to this view, if an ordinary priest learns of a relative's passing while serving, he enters a state of mourning and is forbidden from continuing to offer sacrifices, yet he still may not leave the sanctuary until the service is completed by other priests [רמב״ם מובא בתורה תמימה, מלבי״ם, פרדס יוסף, רד״צ הופמן]. Conversely, others argue that the strict prohibition against leaving the sanctuary applies permanently only to the High Priest. In this view, the remaining sons, Eleazar and Ithamar, received an exceptional warning only because it was the day of their anointing, temporarily granting them the stricter status of a High Priest [ראב״ד מובא בתורה תמימה, מלבי״ם, חזקוני, רד״צ הופמן].
The underlying reason for this strict standard is the anointing oil of God upon them. Through their anointing, the priests cease to be private individuals free to act on their emotions; they are entirely dedicated to their role [ביאור שטיינזלץ, רשב״ם]. Unlike a king's anointing oil, which serves to glorify the king's personal honor, the priest's oil is meant solely to magnify the honor of God. Therefore, in matters concerning God's honor, they must conduct themselves with extreme exactness [העמק דבר]. Moreover, as anointed servants of God, they are forbidden to mourn because the very perception of death changes in the presence of the holy. Before God, there is no true death; the departed has simply moved to a different stage of life [רש״ר הירש מובא ברד״צ הופמן].
In response to this heavy demand, Aaron and his sons suppress their sorrow, display no outward signs of mourning, and remain in the Tabernacle [ביאור שטיינזלץ]. Their absolute obedience is highly praised. They fulfill the command immediately and without questioning its underlying reasons, fully understanding that the instructions given by Moses are the words of God [מלבי״ם, אדרת אליהו, תורה תמימה]. Even if Aaron might have disagreed on a matter of law—perhaps believing that his sons did not actually hold the strict status of a High Priest at that specific time—he set aside his own opinion and acted exactly as he was instructed [העמק דבר].