But the chief priests, taking the pieces of silver, said, "It is not lawful to put them into the treasury, since it is blood money." This scene provides insurmountable evidence of the wickedness of the religious leaders. They had seen fit to use temple funds to pay for the betrayal of Jesus, but now when those funds come back to them they all pretend as if they would never have blood money in the temple treasury. But they had used the temple treasury to pay for His betrayal in the first place.
Think about this. Now, not only has Judas testified to the innocence of Christ, but here is the testimony of the whole Sanhedrin. They said it was blood money, in other words, money illegitimately paid to someone to get someone else killed. They’re so self-righteous, they didn't mind taking it out of the treasury to be blood money, but they acted as if they were too pious to put it back where it came from because it was blood money. They confirm with their own mouths the bloody deed they did in bribing Judas.
The perversity of the plot and the iniquity in their hearts is clear. The hypocrisy continues as they use the blood money to do a charitable work. The potter’s field would be where Gentiles could be buried if they had no money and died while in Jerusalem. Ironically, Judas was the first person who used this field (Acts 1:18-19). The people knew the field was at the price of blood. This was all a part of God’s plan (Jeremiah 18:1-12, 19:1-13, 32:6-9 / Zechariah 11:12-13).
This gives us a picture so that we might understand what the atoning death of Christ means for us. Having seen Jesus condemned by the religious court, you have seen what you ought to receive at the hand of the divine court. Having seen Jesus’ innocence, you should recognize your own guiltiness. Having seen the wickedness of the people, side by side with God’s plan, you ought to bow the knee to God’s sovereignty and realize that Jesus is a substitute for your sin.
The difference between Judas and Peter is that Judas confessed to his co-conspirators, but Peter sought the mercy of Christ. Like them, you are also guilty. But the question is what will you do with the witness of blood?