A.T. Robertson Commentary Acts 19:36

"Seeing then that these things cannot be gainsaid, ye ought to be quiet, and to do nothing rash." — Acts 19:36 (ASV)

Cannot be gainsaid (αναντιρητων ουν οντων). Genitive absolute with ουν (therefore). Undeniable (αν, αντι, ρητος), verbal adjective. Occasionally in late Greek (Polybius, etc.), only here in N.T., but adverb αναντιρητως in Ac 10:29. These legends were accepted as true and appeased the mob.

Ye ought (δεον εστιν). It is necessary. Periphrastic present indicative instead of δε like 1 Peter 1:6; 1 Timothy 5:13f.

Be quiet (κατεσταλμενους). Perfect passive participle of καταστελλω (see verse 35).

Rash (προπετες). Old adjective from προ and πετω, to fall forward, headlong, precipitate. In the N.T. only here and 2 Timothy 3:4, though common in the Koine. Better look before you leap.