It was not in his sleep that the Angel appeared to him, but while he was awake, in the daytime, about the ninth hour. He saw an Angel of God coming in unto him, and saying unto him, Cornelius. And when he looked on him, he was afraid. So occupied was he with himself. Implying, that it was in consequence of the Angel's calling him by a voice that he saw him; as, had he not called him, he would not have seen him: so taken up was he with the act in which he was engaged. But the Angel says to him, Your prayers and your alms have come up for a memorial before God, and now send men to Joppa, and call for one Simon, who is called Peter.
Why does he see the angel? This also was in order to the full assurance of Peter, or rather, not of him, but of the others, the weaker ones. At the ninth hour, when he was released from his cares and was at quiet, when he was engaged in prayers and compunction. And when he looked on him, he was afraid.