The statutes of the LORD are right, rejoicing the heart: the commandment of the LORD is pure, enlightening the eyes. (KJV)
Its amazing that David says that the statutes(commands or decree) of the LORD give the heart joy. We are to obey GOD's law, but it won't be torture, we will enjoy obeying GOD. Enlighten: "to give information to; inform or instruct." We will be guided by HIS commandment because of its purity and holiness.