Luke 23:5 And they were the more fierce, saying, He stirreth up the people, teaching throughout all Jewry, beginning from Galilee to this place. 6 When Pilate heard of Galilee, he asked whether the man were a Galilaean. 7 And as soon as he knew that he belonged unto Herod's jurisdiction, he sent him to Herod, who himself also was at Jerusalem at that time.
Luke 23:8 And when Herod saw Jesus, he was exceeding glad: for he was desirous to see him of a long season, because he had heard many things of him; and he hoped to have seen some miracle done by him.
Luke 23:9 Then he questioned with him in many words; but he answered him nothing.
Luke 23:10 And the chief priests and scribes stood and vehemently accused him.
Luke 23:11 And Herod with his men of war set him at nought, and mocked him, and arrayed him in a gorgeous robe, and sent him again to Pilate.
Luke 23:12 And the same day Pilate and Herod were made friends together: for before they were at enmity between themselves.
Luke may have believed that Jesus needed to visit Herod in order to better fulfil Psalms 2:2 The kings of the earth set themselves, and the rulers take counsel together, against the Lord, and against his anointed, saying, 3 Let us break their bands asunder, and cast away their cords from us (Interpreter's One-Volume Commentary, p. 703).