A.T. Robertson Commentary Acts 4:33

"And with great power gave the apostles their witness of the resurrection of the Lord Jesus: and great grace was upon them all." — Acts 4:33 (ASV)

Gave their witness (απεδιδουν το μαρτυριον). Imperfect active of αποδιδωμ, old verb to give back, to pay back a debt (Luke 7:42), but a late omega form instead of the usual απεδιδοσαν. They kept on giving their witness with power after the answer to their prayer (verse 31).

Of the resurrection (της αναστασεως). It was on this issue that the Sadducees had arrested them (4:1-3).