A.T. Robertson Commentary Acts 26:16

"But arise, and stand upon thy feet: for to this end have I appeared unto thee, to appoint thee a minister and a witness both of the things wherein thou hast seen me, and of the things wherein I will appear unto thee;" — Acts 26:16 (ASV)

Arise and stand (αναστηθ κα στηθ). "Emphatic assonance" (Page). Second aorist active imperative of compound verb (ανιστημ) and simplex (ιστημ). "Stand up and take a stand."

Have I appeared unto thee (ωφθην σο). First aorist passive indicative of οραω. See on Lu 22:43.

To appoint thee (προχειρισασθα σε). See 3:30; 22:14 for this verb.

Both of the things wherein thou hast seen me (ων τε ειδες με). The reading με (not in all MSS.) makes it the object of ειδες (didst see) and ων is genitive of α (accusative of general reference) attracted to the case of the unexpressed antecedent τουτων. Paul is thus a personal eyewitness of the Risen Christ (Luke 1:1; 1 Corinthians 4:1; 1 Corinthians 9:1).

And of the things wherein I will appear unto thee (ων τε οφθησομα σο). Here again ων is genitive of the accusative (general reference) relative α attracted to the case of the antecedent τουτων or εκεινων as before. But οφθησομα is first future passive of οραω and cannot be treated as active or middle. Page takes it to mean "the visions in which I shall be seen by you," the passive form bringing out the agency of God. See those in Ac 18:9; 23:11; 2 Corinthians 12:2. The passive voice, however, like απεκριθην and εφοβηθην, did become sometimes transitive in the Koine (Robertson, Grammar, p. 819).