Luke 20:1
And it came to pass, that on one of those days, as he taught the people in the temple, and preached the gospel, the chief priests and the scribes came upon him with the elders, And it came to pass, that on one of those days, as he taught the people in the temple, and preached the gospel, the chief priests and the scribes came upon him with the elders,
This encounter belongs near the close of His mission. It comes on the day after He drove the sellers out of the temple. He is in the temple teaching the people and preaching the gospel.
The chief priests and the scribes come upon Him with the elders, confronting Him together. They question His right to act in the temple, seeking grounds on which to condemn Him.
He uses the occasion to give the people evidence of His divine mission and to warn them. He knows His efforts to reform the corrupt priesthood will be in vain. In reply He asks whether John's baptism was of divine origin from heaven or of merely human origin.