Leviticus 16:16

Because of the uncleanness of Israel For though the people did not enter into that place, yet their sins entered thither, and would have hindered the effects of the high-priest's mediation on their behalf, if God had not been reconciled to them. In the midst of their uncleanness In the midst of a sinful people, who defile not themselves only, but also God's sanctuary. And God hereby showed them how much their hearts needed to be purified, when even the tabernacle, only by standing in the midst of them, needed this expiation.