John Calvin Commentary Matthew 23:30

"and say, If we had been in the days of our fathers, we should not have been partakers with them in the blood of the prophets." — Matthew 23:30 (ASV)

If we had been in the days of our fathers. Christ did not introduce this sentiment without good reason. For though He does not blame them for the conduct of their fathers, and does not make it the chief ground of accusation that they are the children of murderers, yet He takes a passing glance at their foolish boasting, as they were accustomed to glory in their ancestors while they were descended from the bloody enemies of God.

The appeal may be stated as follows: “You look upon the veneration that you pay to the deceased prophets as some sort of expiation for the wickedness of your fathers. Now then, I have this to urge: it is in vain for you to boast of a sacred ancestry, since you are descended from wicked and ungodly parents. Go now, and screen your crimes by the piety of those whose hands, you acknowledge, were stained with innocent blood. But it is an additional and far more heinous crime that the sacrilegious fury of the fathers, which you condemn by raising sepulchers for the dead, is imitated by you in the murder of the living.”