Ambrose of Milan
Catena Aurea · Lukasevangelium 23
When Pilate heard of Galilee, he asked whether the man were a Galilæan. 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. 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. Then he questioned with him in many words; but he answered him nothing. And the chief priests and scribes stood and vehemently accused him. 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. And the same day Pilate and Herod were made friends together: for before they were at enmity between themselves.
It is not without reason that He is arrayed by Herod in a white robe, as bearing a sign of His immaculate Passion, that the Lamb of God without spot would take upon Himself the sins of the world.