What does it mean to exceed the righteousness of the Pharisees?

In Matthew 5:20, Jesus states that one must have a righteousness that exceeds that of the Pharisees to enter the kingdom of heaven. This righteousness cannot be earned through human effort or by adhering to the law selectively, as the Pharisees did. Instead, it is the righteousness that comes through faith in Christ, who perfectly fulfilled the law on behalf of sinners. Believers are robed in His righteousness and thus stand accepted before God, surpassing the hypocritical and superficial righteousness exemplified by the Pharisees.