A.T. Robertson 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 witness with them (συνεπιμαρτυρουντος του θεου). Genitive absolute with the present active participle of the late double compound verb συνεπιμαρτυρεω, to join (συν) in giving additional (επ) testimony (μαρτυρεω). Here only in N.T., but in Aristotle, Polybius, Plutarch.

Both by signs (σημειοις τε κα)

and wonders (κα τερασιν)

and by manifold powers (κα ποικιλαις δυναμεσιν)

and by gifts of the Holy Ghost (κα πνευματος αγιου μερισμοις). Instrumental case used with all four items. See Ac 2:22 for the three words for miracles in inverse order (powers, wonders, signs). Each word adds an idea about the εργα (works) of Christ. Τερας (wonder) attracts attention, δυναμις (power) shows God's power, σημειον reveals the purpose of God in the miracles. For ποικιλαις (manifold, many-coloured) see Mt 4:24; James 1:2. For μερισμος for distribution (old word, in N.T. only here and Heb 4:12) see 1 Corinthians 12:4–30.

According to his own will (κατα την αυτου θελησιν). The word θελησις is called a vulgarism by Pollux. The writer is fond of words in -ις.