Jamieson, Fausset and Brown on Acts 26:16-18

16-18. But rise, &c.--Here the apostle appears to condense into one statement various sayings of his Lord to him in visions at different times, in order to present at one view the grandeur of the commission with which his Master had clothed him [Alford].

a minister ... both of these things which thou hast seen--putting him on a footing with those "eye-witnesses and ministers of the word" mentioned in Lu 1:2.

and of those in which I will appear to thee--referring to visions he was thereafter to be favored with; such as Ac 18:9, 10; 22:17-21; 23:11; 2Co 12:1-10, &c. (Ga 1:12).