Jamieson, Fausset and Brown on Acts 10:17-24

17-24. while Peter doubted ... what this should mean, behold, the three men ... stood before the gate ... and asked--"were inquiring," that is, in the act of doing so. The preparations here made--of Peter for his Gentile visitors, as of Cornelius for him--are devoutly to be noted. But besides this, at the same moment, "the Spirit" expressly informs him that three men were inquiring for him, and bids him unhesitatingly go with them, as sent by Him.