John Calvin on Acts 10:3

3. He saw in a vision. Luke putteth vision for a kind of oracle coming from God, that we may know that Cornelius was brought unto the faith of Christ after an heavenly manner. And because men are oftentimes deceived with juggling, Luke setteth down the time to avoid all suspicion, when he mentioneth the ninth hour. And at that time they were wont to divide the day into twelve hours; from the rising of the sun until the going down thereof. Whereupon it followeth that it was fair daylight when the angel appeared, that the vision might be more evident. Although there were always seals added unto visions, that they might free the servants of God from fear of illusions, because when he appeared in dreams, yet were there such marks of certainty imparted in their minds as would not suffer them to doubt.