It was therefore necessary,.... On account of the divine appointment, and that types and antitypes might correspond; and especially it was necessary with respect to the Messiah, the substance and body of all types.
So Jonathan ben Uzziel paraphrases the text in Ex 40:9:"and thou shalt take the anointing oil, and thou shalt anoint the tabernacle, and all that is in it; and thou shall sanctify it, lwjm, because of the crown of the kingdom of the house of Judah, and the King Messiah, who shall redeem Israel in the latter days.'
'Upon his account it was necessary,that the patterns of things in the heavens should be purified with these; that is, that all the people, and the book of the covenant, and the tabernacle, and its vessels, which were types and patterns of persons and things in Gospel churches, should be purified with blood and water, and with scarlet wool and hyssop.
But the heavenly things themselves, with better sacrifices than these; the sum and substance of the above patterns, shadows, and examples, such as heaven itself; which though not impure in itself, yet some think it, may be said to be purified, because saints are made meet for it, by being purged with the blood of Christ; others observe, that sin reaches to heaven, and provokes God that dwells there; hence atonement for it may be called a purification of heaven: but rather this may be said of it, inasmuch as by the blood of Christ an entrance and preparation is made for the saints into it.
Likewise, the human nature of Christ is among these heavenly things; not that it is heavenly, as to the matter and substance of it, but may be so called, because of its wonderful formation; and which has been purified, not from any real internal pollution that was in it, but from what was imputed to it, the sin of his people.
Also the whole church, triumphant and militant, may be intended by heavenly things: the Old Testament saints went to heaven before Christ came; and though they were not impure, but were the spirits of just men made perfect, yet their iniquities were purged by the blood and sacrifice of Christ, after they were gone to heaven; see Heb 9:15.