From: Matthew 23:27-32
Jesus Indicts the Scribes and Pharisees (Continuation)
(Jesus said to the scribes and Pharisees,)  "Woe to you, scribes and Pharisees, hypocrites! for you are like white-washed tombs, which outwardly appear beautiful, but within they are full of dead men's bones and all uncleanness.  So you also outwardly appear righteous to men, but within you are full of hypocrisy and iniquity.
 "Woe to you, scribes and Pharisees, hypocrites! for you build the tombs of the prophets and adorn the monuments of the righteous,  saying, `If we had lived in the days of our fathers, we would not have taken part with them in shedding the blood of the prophets.'  Thus you witness against yourselves, that you are sons of those who murdered the prophets.  Fill up, then, the measure of your fathers."
27-28. The Jews used to whitewash tombs annually, shortly before the feast of the Passover. The whitewash made the tombs more visible and helped to avoid people brushing against them, which would have meant incurring legal uncleanness for seven days (Numbers 19:16; Luke 11:44).
In the sunlight, these tombs sparkled radiantly white, but inside they held corruption.
29-32. Our Lord shows them that they are cut off from the same cloth as their ancestors--not because they erect mausoleums in honor of prophets and just men but because they are guilty of the same sin as those who killed the prophets. Hence their hypocrisy, which makes them even worse than their fathers. With pained irony Jesus tells them that they are compounding the sins of their ancestors.
Clearly this is referring to His passion and death: if the ancients killed the prophets, by causing Him to suffer and die our Lord's contemporaries will still be more cruel.
Source: "The Navarre Bible: Text and Commentaries". Biblical text taken from the Revised Standard Version and New Vulgate. Commentaries made by members of the Faculty of Theology of the University of Navarre, Spain. Published by Four Courts Press, Kill Lane, Blackrock, Co. Dublin, Ireland. Reprinted with permission from Four Courts Press and Scepter Publishers, the U.S. publisher.