A.T. Robertson Commentary Luke 20:1

"And it came to pass, on one of the days, as he was teaching the people in the temple, and preaching the gospel, there came upon him the chief priests and the scribes with the elders;" — Luke 20:1 (ASV)

On one of the days (εν μια των ημερων). Luke's favourite way of indicating time. It was the last day of the temple teaching (Tuesday). Luke 20:1–19 is to be compared with Mr 11:27-12:12; Matthew 21:23–46.

There came upon him (επεστησαν). Second aorist active indicative, ingressive aorist of εφιστημ, old and common verb, stood up against him, with the notion of sudden appearance. These leaders (cf. 19:47) had determined to attack Jesus on this morning, both Sadducees (chief priests) and Pharisees (scribes), a formal delegation from the Sanhedrin.