John Chrysostom

He had said against the Scribes and Pharisees, that they were the children of those who killed the Prophets; now therefore He shews that they were like them in wickedness, and that that was false that they said, If we had been in the days of our fathers, we would not have been partakers with them in the blood of the Prophets. Wherefore He now says, Fill ye up the measure of your fathers. This is not a command, but a prophecy of what is to be.