Matthew 23:31-35

Mat 23:31 (KJB)
Wherefore ye be witnesses unto yourselves, that ye are the children of them
which killed the prophets.

When the Pharisees had built the monuments on the tombs of the slain prophets, Jesus was basically telling them that because of this act, they were identifying themselves with the same mindset the ones who killed the prophets had. There would act no more responsibly than their forefathers. (Acts 7:52 KJV) Which of the prophets have not your fathers persecuted? and they have slain them which showed before of the coming of the Just One; of whom ye have been now the betrayers and murderers: Stephen put the same question to them concerning their identification with those who slew the prophets but he accuses this same group of slaying the Lord Jesus Christ.

Mat 23:32 (KJB)
Fill ye up then the measure of your fathers.

(Gen 15:16 KJV) But in the fourth generation they shall come hither again: for the iniquity of the Amorites is not yet full. God sets a limit on sin and Jesus is now telling the religious leaders that they are in essence completing the fullness of sin which their forefathers started. Once they have done this then judgment will come to them as it did to the Amorites when their sin limit was reached.

Mat 23:33 (KJB)
Ye serpents, ye generation of vipers, how can ye escape the damnation of hell?

Generation - Offspring

Jesus calls them serpents and He also refers to them as offspring or children of vipers. (Mat 3:7 KJV) But when he saw many of the Pharisees and Sadducees come to his baptism, he said unto them, O generation of vipers, who hath warned you to flee from the wrath to come? John the Baptist had seen them as the same thing. By means of both Jesus and John using the snake, they were telling the Pharisees that they were children of the devil and since they choose to remain in the condition, then how were they going to escape the damnation of hell since salvation only comes through the Lord Jesus Christ, the very one they were seeking to kill. (John 8:44 KJV) Ye are of your father the devil, and the lusts of your father ye will do. He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father of it.

Mat 23:34 (KJB)
Wherefore, behold, I send unto you prophets, and wise men, and scribes: and some of them ye shall kill and crucify; and some of them shall ye scourge in your synagogues, and persecute them from city to city:

Here Jesus reveals to them that He is deity. They don’t see it but when Jesus says that “I send…” it means that as the second person of the Godhead, He has the authority to dispatch prophets to bring messages to a nation. Just as Jesus sent out the prophets in the Old Testament to Judah and Israel, He will be sending to Israel prophets, wise men, and scribes. “I send” is in the present tense so Jesus will be sending them consistently and they will be in the form of believers who will be redeemed through His blood. By their attitude toward Jesus and His followers, they were literally filling the cup of iniquity which their forefathers had started to fill. It would be completed in their generation because they will launch a hate campaign against all the believers. Much of this happened during the ministry of the Apostle Paul when they would persecute him from city to city. In fact it was Jews from Asia which pulled Paul out of the Temple in Acts 21 and this act led to the eventual martyrdom of Paul. They stoned Stephen. They had Peter and some of the Apostles beaten in the synagogue. As much as the Pharisees did to try and stop the spread of Christianity, it was impossible to stop and it continued to grow.

Mat 23:35 (KJB)
That upon you may come all the righteous blood shed upon the earth, from the blood of righteous Abel unto the blood of Zacharias son of Barachias, whom ye slew between the temple and the altar.

By killing the newest of these prophets, the Pharisees would fill up the measure of the cup of sin and because of this would be held accountable for all the righteous blood they and their forefathers shed. Since Jesus is placing their condemnation in the present tense including accountability from the time of Abel to the man Zacharias, his identification still remains a mystery. It does not matter because if Jesus stated these religious leaders had killed him in the temple, then their condemnation will be just. It could not be the prophet Zechariah because there is no record of him dying in the fashion. There is also a Zechariah mentioned in 2 Chronicles 24 but he is the son of Jehoiada the priest.