Charles Ellicott Commentary Acts 10:3

"He saw in a vision openly, as it were about the ninth hour of the day, an angel of God coming in unto him, and saying to him, Cornelius." — Acts 10:3 (ASV)

In a vision, evidently. The adverb seems added to distinguish the manifestation from that of a dream like Joseph’s in Matthew 1:20; Matthew 2:13, or of a trance like St. Peter’s (Acts 10:10) or St. Paul’s (Acts 22:17).

About the ninth hour of the day. This was, as in Acts 3:1, one of the three hours of prayer, the hour when the evening sacrifice was offered in the Temple. Cornelius had therefore, thus far, accepted the Jewish rules of devotion, and for him also the Law was a schoolmaster bringing him to Christ.