John Calvin Commentary Acts 5:9

"But Peter [said] unto her, How is it that ye have agreed together to try the Spirit of the Lord? behold, the feet of them that have buried thy husband are at the door, and they shall carry thee out." — Acts 5:9 (ASV)

To tempt the Spirit. He expresses the same thing in other words that he had said before: namely, that they mocked God irreverently and contemptuously.

But he said that they tempted the Spirit because they had cunningly contrived their deceit, as if the Spirit of God were not the knower of the hearts. For it showed extreme carelessness that, having confided in each other about their wickedness, they made their pact between themselves, as it were, excluding God. Scripture says that God is tempted either when his power is diminished, or when the knowledge of all things is denied him.

Furthermore, he means that Spirit who governed the Church through the apostles. For when Christ says, When the Spirit cometh, he shall judge the world, he indicates no other kind of authority than that which he exercises through the ministry of the Church.