John Calvin Commentary Acts 4:30

"while thy stretchest forth thy hand to heal; and that signs and wonders may be done through the name of thy holy Servant Jesus." — Acts 4:30 (ASV)

Grant unto thy servants. Seeing that one miracle had stung the enemy so severely, why do these holy men desire to have new miracles performed daily? Therefore, we gather from this what I have already touched upon: that they hold the glory of God in such high regard that, in comparison to this, they value all other things lightly.

They have regard for this one thing only: that the power of God may be declared by miracles, which the godly ought always to desire, although the adversaries burst with anger, and all of hell rages. We must also think the same of boldness to speak. They knew that the wicked could tolerate nothing worse than the free course of the gospel; but because they know that it is the doctrine of life which God wills to be published whatever happens, they undoubtedly prefer its preaching above all other things, because it is acceptable to God.

And we are taught that we then rightly acknowledge the benefits of God as we ought, if on this occasion we are spurred on to pray that He will confirm what He has begun. The apostles had shown a sign of heroic fortitude; now again they pray that they may be equipped with boldness.

So Paul desires the faithful to pray to the Lord that his mouth may be opened, even though his voice already resounded everywhere (Ephesians 6:19). Therefore, the more we perceive ourselves to be helped by the Lord, let us learn to ask of God that we may continue to advance; and especially since the free confession of the gospel is a unique gift of God, we must continually implore Him to keep us in it.