When the Tabernacle stood finished in the wilderness and every board was raised into place, the Holy One turned Moses's attention from the walls to the men who would serve inside them. The command came at Exodus 40:15 through the voice of Targum Pseudo-Jonathan, the Aramaic paraphrase composed in the land of Israel and preserved in a single manuscript in the British Library: anoint Aaron's sons as you anointed their father, that they may minister before Me.
The oil was not a courtesy. It was the hinge on which an entire family line turned. One pour of the sacred compound shemen ha-mishchah transformed ordinary Levites into priests whose descendants would serve in the <a href='/categories/midrash-aggadah.html'>sanctuary</a> for as long as Israel worshipped. The Targum underlines the phrase "perpetual priesthood in their generations" (Exodus 40:15) — a consecration that would outlive the men themselves.
Why anoint the children at all?
Aaron had already received the oil directly. Why insist on pouring it over his sons? Because the priesthood was not a personal gift. It was a covenant held in trust. The father could serve for decades, but the moment he died, the office had to pass intact. Anointing the sons now, while the Tabernacle still smelled of fresh cedar, meant the fire on the altar would never go out for lack of a qualified hand.
What "perpetual" meant in practice
The Hebrew olam and its Aramaic equivalents do not always mean eternity. Sometimes they mean "as long as the age endures." But the rabbis read this verse maximally. The priesthood anointed here would continue through the Tabernacle at Shiloh, through Solomon's Temple, through the Second Temple, and — the sages insisted — into the Temple that is yet to be rebuilt. The oil, prepared once in the wilderness, carried enough sanctity to last.
The takeaway: holiness is rarely a solo act. Aaron's service meant nothing without sons ready to carry it forward, and a single anointing in the desert was meant to reach across every generation that would ever stand at the altar.