4 If he were limited to earth, he wouldn't even be a priest. We wouldn't need him since there are plenty of priests who offer the gifts designated in the law. 5 These priests provide only a hint of what goes on in the true sanctuary of heaven, which Moses caught a glimpse of as he was about to set up the tent-shrine. It was then that God said, "Be careful to do it exactly as you saw it on the Mountain."
Matthew Henry's Commentary on Hebrews 8:4-5
Commentary on Hebrews 8:1-6
(Read Hebrews 8:1-6)
The substance, or summary, of what had been declared was, that Christians had such a High Priest as they needed. He took upon himself human nature, appeared on earth, and there gave himself as a sacrifice to God for the sins of his people. We must not dare to approach God, or to present any thing to him, but in and through Christ, depending upon his merits and mediation; for we are accepted only in the Beloved. In all obedience and worship, we should keep close to God's word, which is the only and perfect standard. Christ is the substance and end of the law of righteousness. But the covenant here referred to, was that made with Israel as a nation, securing temporal benefits to them. The promises of all spiritual blessings, and of eternal life, revealed in the gospel, and made sure through Christ, are of infinitely greater value. Let us bless God that we have a High Priest that suits our helpless condition.