Therefore leaving the principles of the doctrine of Christ, let us go on unto perfection; not laying again the foundation of repentance from dead works, and of faith toward God [Heb. 6:1].
"“Leaving the principles of the doctrine of Christ” is literally “leaving the word of the beginning concerning Christ.” For a builder it means to leave the foundation and go up with the scaffolding, or for a child in school to go on from his ABCs to work on his B.A. or Ph.D. It is preparing believers for a trip up to the throne of God.
“Let us go on” is horizontal, not perpendicular.
“Unto perfection” is maturity, full age.
There are six foundational facts in the Old Testament which prefigure Christ in ritual, symbol, and ceremony: (1) repentance from dead works; (2) faith toward God; (3) doctrine of baptisms; (4) laying on of hands; (5) resurrection of the dead; and (6) eternal judgment.
“Repentance from dead works.” The works were the works of the Mosaic Law. They were continually trying to keep the Law, then breaking it, then repenting. That is baby stuff, the writer tells them.
“And of faith toward God.” The Old Testament taught faith toward God; so just to say you believe in God doesn’t mean you have come very far. The Old Testament ritual presented a faith in God by approaching Him through the temple sacrifices, not through Christ as High Priest."
Of the doctrine of baptisms, and of laying on of hands, and of resurrection of the dead, and of eternal judgment [Heb. 6:2].
"“Doctrine of baptisms [washings]” has nothing to do with New Testament baptism. They refer to the washings of the Old Testament ritual, and there were many of them. The Hebrew believers were wanting to return to these things which were only shadows; they were the negatives from which the spiritual pictures were developed. They prefigured Christ, the reality.
“Laying on of hands.” This was also an Old Testament ritual. When a man brought an animal offering, he laid his hands on its head to signify his identification with it. The animal was taking his place on the altar of sacrifice.
“Resurrection of the dead” was taught in the Old Testament, but now they needed to come up to the resurrection of Christ and to the living Christ.
“Eternal judgment” was taught in the Old Testament."
McGee, J. Vernon: Thru the Bible Commentary. electronic ed. Nashville : Thomas Nelson, 1997, c1981, S. 5:543
 

"8:17 laid hands on them. This signified apostolic affirmation and solidarity. See note on 6:6. received the Holy Spirit. That this actually occurred likely demonstrated that believers also spoke in tongues here, just as those who received the Spirit did on the Day of Pentecost (see note on 2:4), as the Gentiles did when they received the Spirit (10:46), and as those followers of John did (19:6). As Samaritans, Gentiles, and believers from the Old Covenant were added to the church, the unity of the church was established. No longer could one nation (Israel) be God’s witness people, but the church made up of Jews, Gentiles, half-breed Samaritans, and OT saints who became NT believers (19:1–7). To demonstrate the unity, it was imperative that there be some replication in each instance of what had occurred at Pentecost with the believing Jews, such as the presence of the apostles and the coming of the Spirit manifestly indicated through speaking in the languages of Pentecost (2:5–12)."

MacArthur, John Jr: The MacArthur Study Bible. electronic ed. Nashville : Word Pub., 1997, c1997, S. Ac 8:17

"19:6 Paul … laid hands on them. This signified their inclusion into the church (see note on 8:17). Apostles were also present when the church was born (chap. 2), and when the Samaritans (chap. 8) and Gentiles (chap. 10) were included. In each case, God’s purpose was to emphasize the unity of the church. spoke with tongues and prophesied. This served as proof that they were part of the church (see note on 8:17). They also needed tangible evidence that the Holy Spirit now indwelt them, since they had not heard that He had come (v. 2)."

MacArthur, John Jr: The MacArthur Study Bible. electronic ed. Nashville : Word Pub., 1997, c1997, S. Ac 19:6