Some have said that the scriptures are God's instruction manual for our lives and, while I understand the allegorical reference, an instruction manual is something that allows us to operate a device without having to know or depend on its creator. When we read the operators manual for a car, we learn how to operate it, completely without ever having to talk with its creators or designers. The scriptures are not such. While the scriptures illuminate our path, they do not supplant our need for a relationship with our creator.
David describes the scriptures, not as a searchlight illuminating his entire life or a map showing every twist and turn his life would take, but a simple light; one that illuminates immediately around his feet, that he might walk without slipping and stumbling. James recognizes that "we all stumble in many ways." (James 3:2) and he characterizes such stumbling as moral failure. The light of the scripture is a moral light guarding our steps lest we should morally stumble and fall. This is why David said, "Your word I have hidden in my heart, that I might not sin against You." (Psalms 119:11 NKJV) David knew that God's word would guard him and illuminate his path, showing the dangers and pit falls that lay around him and counseling him to avoid them that he might not stumble or fall in any way.
Most of us have prayed many times the words of Jesus when he taught us to say, "And do not lead us into temptation, but deliver us from evil." (Matthew 6:13) One of the primary tools the Lord uses to "lead us not into temptation" is His scriptures. The scriptures, in many different forms and methods, are set to lead us away from temptation and towards righteousness. For example, by its commands, "Do not lie to one another." (Colossians 3:9), by its exhortations, "flee from youthful lusts and pursue righteousness." (2 Tim 2:22), and by its wisdom, "Can a man take fire in his bosom and his clothes not be burned?" (Proverbs 6:27) By these and may other ways the scriptures protect us from stumbling and enable us to stand upon a firm footing that is Christ and His teachings.
How many of us have prayed that prayer, asking God to lead us away from temptation, yet have never availed ourselves to the light that is His scriptures; a light that is clear and precise, a light that can expose our hidden heart, and a light that can bring life and healing to us and to our way. The writer of Hebrews describes the word of God as, "living and active and sharper than any two-edged sword, and piercing as far as the division of soul and spirit, of both joints and marrow, and able to judge the thoughts and intentions of the heart. And there is no creature hidden from His sight, but all things are open and laid bare to the eyes of Him with whom we have to do." (Hebrews 4:12-13) If we are to live as moral being then we must learn to live according to His word.