John Calvin Commentary Hebrews 2:4

"God also bearing witness with them, both by signs and wonders, and by manifold powers, and by gifts of the Holy Spirit, according to his own will." — Hebrews 2:4 (ASV)

God also bearing them witness, etc. The Apostles received what they preached from the Son of God. In addition to this, the Lord also demonstrated His approval of their preaching through miracles, as if by a solemn endorsement. Therefore, those who do not reverently receive the Gospel, recommended by such testimonies, disregard not only the word of God but also His works.

To emphasize their importance, He designates miracles by three names. They are called signs because they rouse people’s minds so that they may think of something higher than what appears; and wonders, because they present what is rare and unusual; and miracles, because the Lord shows in them a singular and extraordinary evidence of His power.

Regarding the phrase bearing witness, or attesting, it points out the right use of miracles: specifically, that they serve to establish the Gospel. For almost all the miracles performed in all ages were, as we find, for this purpose: that they might be the seals of God’s word. How much more strange, then, is the superstition of the Papists, who employ their own fictitious miracles for the purpose of overthrowing the truth of God.

The conjunction συν, together with, has this meaning: that we are confirmed in the faith of the Gospel by the joint testimony of God and humans, for God’s miracles were testimonies concurring with the voice of humans.

He adds, by the gifts or distributions of the Holy Spirit, by which the doctrine of the Gospel was also adorned, and of which they were the accompaniments. For why did God distribute the gifts of His Spirit, except in part that they might be helps in proclaiming it, and in part that they might, through admiration, move the minds of people to obey it? Hence Paul says that tongues were a sign to unbelievers. The words, according to His will, remind us that the miracles mentioned could be ascribed to no one except God alone, and that they were not performed without design but for the specific purpose of sealing the truth of the Gospel.