A.T. Robertson Commentary Acts 18:20

"And when they asked him to abide a longer time, he consented not;" — Acts 18:20 (ASV)

When they asked him (ερωτωντων αυτων). Genitive absolute of present participle of ερωταω, old verb to ask a question, common in Koine to make a request as here.

He consented not (ουκ επενευσεν). First aorist active indicative of επινευω, old verb to express approval by a nod, only here in the N.T.