‘He saw in a vision openly, as it were about the ninth hour of the day, an angel of God coming in to him, and saying to him, “Cornelius.” '
Cornelius was in his own home when he saw a vision. Cornelius was a common Roman name. And this man was praying at the regular time of prayer (the ninth hour), which we may presume was his custom. He was a God-fearer. At that time he saw in a vision an angel of God, who came to him and spoke with him, addressing him by name. Three in the afternoon (fifteen hundred hours) was not a time for dreaming.
‘An angel of God.' This indicates a more direct and more physical messenger than the Spirit, which was necessary because Cornelius was not yet a man of the Spirit. The coming of an angel of God speaking a person's name takes us right back to Luke 1:11; Luke 1:28. It is indicative in Luke of something that is to happen which is vital for the future. See also Acts 5:19; Acts 8:26; Acts 12:7, where however he is an ‘angel of the Lord', for there it was in respect of believers.