What does Matthew 23:19 mean?

Jesus has called the scribes and Pharisees blind guides (Matthew 23:16), blind fools (Matthew 23:17), and now simply calls them blind. Their ranking of some oaths as binding and others as non-binding shows their complete lack of understanding about what belongs to God and what it means to swear an oath (Matthew 23:13–15).

Using a traditional scheme of loopholes and technicalities, these religious leaders have declared that swearing by the gold of the temple or swearing by the sacrifice on an altar requires a person to keep their word. In contrast, they say, swearing by the temple or altar themselves is somehow non-binding. Jesus has pointed out that the temple that makes the gold sacred, just as the altar makes the sacrifice sacred. The scribes and Pharisees, of all people, should understand that all these things come from God and belong to God. These supposedly learned men don't have any basis to declare one sacred and another not.

While not stated directly, this "woe" also underscores Jesus' prior criticism of using oaths to enhance a promise. Why encourage anyone to take an oath, to swear by something sacred, for any reason? Why not just teach people to keep their plain word when they say "yes" or "no?" Anything more than that, as Jesus taught in the Sermon on the Mount, comes from evil (Matthew 5:33–37).