Acts 5:32

Acts 5:32. And we are his witnesses of these things. ‘His,' as appointed by Him, as chosen by Him when on earth. ‘Of these things,' viz. the death on the accursed tree and the ascension from earth, they were eye-witnesses; but they were witnesses in a yet higher sense of their Master's exaltation, as conscious of the Holy Ghost, which He promised should descend upon them when once He had ascended, and which, in accordance with the promise, fell on them at Pentecost and gave them their new grand powers.

And so is also the Holy Ghost. The Holy Ghost, too, is joined with them as a witness. His solemn testimony is publicly borne by those miracles performed by the apostles through His power.