In their zeal to avoid breaking the Law the Pharisees substituted their interpretation of the Law for the Law itself. As a result, they lost sight of its original intent. This is where Jesus enters the conversation. He is the Second Moses come not to nullify the Law, but to fulfill it by restoring its original intent. According to Jesus, the original intent of the Law with respect to oaths is this: practice the truth, the whole truth, and nothing but the truth in everything you say and do.