Before the altar of the Mishkan could receive Israel's offerings, it had to be made holy itself. Targum Pseudo-Jonathan (an Aramaic paraphrase whose expansions preserve tannaitic and amoraic traditions) records the instruction: every day of the seven-day inauguration, a bullock was to be offered as a sin offering, and its blood was to anoint the altar — a daily consecration, layered like oil on stone, until the altar itself was saturated with atonement.
The ancient rabbis noticed something strange here. Why does the altar need a sin offering? Stone does not sin. Wood does not transgress. The answer the sages offered: the altar does not sin, but it bears sin. Every offering brought to it carries the weight of human failure, and even the stones of a holy place absorb something of what passes across them. The daily bullock was not for the altar's guilt. It was for the altar's capacity — preparing it to hold the guilt of a nation.
This is why Moses anointed it as he offered atonement upon it. The two acts were one motion: the oil sanctifying, the blood atoning, the altar becoming what Israel needed it to be (Exodus 29:36). Seven days, because holiness in Jewish thought is never achieved in a single gesture. It is built in layers, like the seven days of creation itself.
The Maggid hears in this a teaching about preparing any sacred space — a home, a heart, a moment of prayer. You do not walk in clean. You clean as you walk, day by day, until the place itself learns to hold what you bring.