Heb 8:1. Sum is from KEPHALAION which Thayer defines, "The chief or main point, the principal thing." It refers to what Paul said in the: preceding chapter, together with w h at follows in the present one, concerning the priesthood of Christ. Such an high priest has virtually the same significance as sum. The Levitical priests served in Jerusalem while Christ is at the right hand of his Father. Majesty pertains to the greatness of the throne of God. In the heavens has the same significance as "higher than t h e heavens" in chapter 7:26.
Heb 8:2. The building used in the Mosaic system was regarded as a sanctuary (holy place) and a tabernacle as truly as is the one in the service under Christ. The difference is in the description given in the rest of this verse. True tabernacle means that of which the first one was a type.
tched is defined by Thayer as follows: "To make fast, to fix; to fasten together, to build by fastening together." The Lord directed the building of the Old Testament tabernacle, but it was made of literal material and the work was actually done by human hands (See Exodus 36-40.) The last tabernacle employed the services of man also, but the materials were not literal and the formation of the system was the handiwork of God.
Heb 8:3. Every high priest refers to those under the Old Testament line. Thayer defines ordained, "To appoint one to administer an office." Gifts and sacrifices were in the same general class, but the first refers especially to articles that were not intended to be used as victims on the altar. This man means Christ who was called upon to make a somewhat offering. That is, Christ offered many contributions to the New Testament service, and then made the "supreme sacrifice" of himself on the cross just before ascending from earth to his Father in Heaven.
Heb 8:4. If he were on earth. This means as long as Christ was on earth he could not act as a priest. That is because the law was in force all the time He was on earth, and it already had its priests to offer according to that law.
Heb 8:5. The institutions of the Mosaic system were examples and shadows (patterns or types) of the heavenly things (t h e institutions under Christ). Who means the priests mentioned in the preceding verse. In Exo 25:40 is the instruction that God gave Moses to make all things according to the "pattern" shown to him in the mount. The idea is that when God mentioned this pattern for the tabernacle service, He had in mind that it was to be a type or pattern of the greater things to come, as well as to serve the purpose of that first dispensation.
Heb 8:6. Several words of comparison in the second degree are used in this verse which should not be misapplied. God never made any mistakes and all that He ever did was good from the standpoint of being righteous. But the purposes to be accomplished by His plans were not always considered as final. He had a terminal to be reached in the preparation of mankind for the Hereafter, and until the final plan had been reached (that which was "perfect" 1Co 13:10), each step in the unfolding of the divine plan may be considered as looking forward to something 'more excellent and better.
Heb 8:7. A part of the fault of which the Lord complained was concerning the shortcomings of the people. They did not do even as well as they could with the system which God had given them. However, God has always been inclined to give His creatures every opportunity for developing a desirable character. In view of this, He regarded the old law as not the best that could be accomplished in the future, and in that sense He would not consider the old covenant to be faultless.
Heb 8:8. (recorded in 1 Kings 12). The tribes were destined to be reunited after the captivity, but the two parts are named to show that every Jew (as well as the Gentiles) was to be included in the new covenant.
Heb 8:9. The day refers to the period in general when Sinai was the principal place of interest. (See Jer 34:13-14.) The shortcomings of the Israelites was the reason on the human side for a change. (See verse 7.)
Heb 8:10 : This verse states one of the main differences between the old and the, new covenant. When a male child was eight clays old he was cir-cumcized. and that made him a full member of the covenant, notwithstanding he had no mind to receive anything: the law was put in the flesh instead of the mind. The new covenant laws were to be put in the mind (or heart) instead of the flesh.
Heb 8:11. Samuel was a full "brother" to Eli although he "did not yet know the Lord" (1Sa 3:7); his circumcision introduced him into the brotherhood (Gen 17:9-14). That is why it was necessary for Eli to make his brother Samuel acquainted with the Lord. It was done in verse 9 of the same chapter where he told Samuel to say, "Speak, Lord: for thy servant heareth," which is the same as know the Lord in our present verse. Such an introduction in the brotherhood under Christ will not be necessary because all shall know me from the least to the greatest. That is because under the New Testament system a person cannot become a member until he is old enough and has mind enough to receive the law of Christ intelligently. This would completely rule out all such conditions as "cradle rolls" or infant church membership in the New Testament church. All must have mind enough to "know the Lord" through the law of the Gospel before they can come into the church.
Heb 8:12. This verse contains a likeness and a contrast between the two covenants. God showed mercy under the old, and the passages that show It are too numerous to mention. (It should be stated what was overlooked at verse 10, that another likeness between them is that in each case the relation of God and people holds good.) The contrast in this verse is that the sins would be remembered no more. The word "against" Is often added in quoting this subject which is incorrect, for God never did remember a sin against a man after he had been forgiven. This point will be dealt with in detail by the comments on chapter 10:3.
Heb 8:13. The main point in this verse is a conclusion based on the term new covenant: it proves that the other one was considered old. Since old things are expected to disappear. the conclusion is that the old covenant was to be replaced by the New Testament.
Zerr, E.M. "Commentary on Hebrews 8". E.M. Zerr's Commentary on Selected Books of the New Testament. https://www.studylight.org/commentaries/eng/znt/hebrews-8.html. 1952.