What does Matthew 23:16 mean?

Jesus continues His condemnation of Israel's religious leaders, specifically the groups known as the scribes and the Pharisees. These were the primary self-professed teachers of Jewish law and spirituality. As the judge ordained by God (John 5:22), Jesus is pronouncing a series of "woes" against them. He now comes to the third such condemnation.

Highlighting their hypocrisy (Matthew 13:13) and false teaching (Matthew 23:15), Jesus repeats His criticism of these men as blind guides (Matthew 15:12–14; John 9:39–41). These religious leaders cannot hope to lead anyone to the correct conclusions since they can't see the truth themselves.

The specific example Christ gives of this spiritual blindness involves the taking of oaths in binding agreements. Swearing oaths was deeply built into the culture of this time, though it's not a practice most modern people understand. Under the ancient understanding, the responsibility of an oath was directly related to the power or sacredness of the object—or person—by which the oath was taken. During this period, the Israelites were not allowed to swear oaths on God Himself or even to speak the name of God directly. Instead, they would swear oaths by objects closely connected to God in some way, such as His throne, or the temple, or the altar.

Wallowing in legalism and loopholes, the Pharisees had apparently devised a system separating objects which would "truly" bind someone to their promise from objects not significant enough to require one to keep their word. This allowed a crafty person to swear an oath by something non-binding, leaving room to be deceptive about doing as they said. Jesus' example is one of those distinctions: If someone swears by the temple, it was not a meaningful oath, but if someone swore by the gold of the temple, he or she was bound to do what was agreed to.

Jesus has already condemned the practice of taking oaths to lend weight to one's word. During the Sermon on the Mount, He declared such tacked-on promises as unnecessary and as coming from evil. Instead, He insisted that people simply say "yes" and "no" and then do what they said (Matthew 5:33–37).

In these verses, the immediate criticism is how the Pharisees wrongly assign value according to worldly standards, not the standards of God.