And we are his witnesses of these things; and so is also the Holy Ghost, whom God hath given to them that obey him. We are his witnesses - The word αυτου, his, is omitted by AD, and several others of good note; the Syriac, all the Arabic, Ethiopic, and Vulgate. It does not seem to be necessary.
Of these things - Των ῥηματων τουτων, Of these transactions: i.e. of Christ's life and miracles, and of your murderous proceedings against him.
And so is also the Holy Ghost - In the gift of tongues lately communicated; and by his power and influence on our souls, by which we are enabled to give irresistible witness of our Lord's resurrection.
To them that obey him - We obey God, not you; and therefore God gives us this Spirit, which is in us a fountain of light, life, love, and power.
The Spirit of God is given to the obedient: in proportion as a man who has received the first influences of it (for without this he cannot move in the spiritual life) is obedient to those influences, in the same proportion the gifts and graces, the light, life, and power, of the Holy Spirit, are increased in his soul.