The problem presented in this passage is it identifies our weakness/inability to satisfy the requirements of an altogether righteous and set apart God on our own. We simply can’t. If it’s up to us, boundaries must be set up, rigid practices must be imposed. Even in that, we will make promises “to do all that is commanded” only to find ourselves missing the mark time and time again. The beauty of this passage is that it sets us up to see our need for Jesus. Without Jesus, we cannot approach the mountain. Without Jesus, we cannot wash our clothes enough times to make us clean enough to fully encounter God.