Jamieson, Fausset and Brown on Psalms 119:105

105. Not only does the Word of God inform us of His will, but, as a light on a path in darkness, it shows us how to follow the right and avoid the wrong way. The lamp of the Word is not the sun. He would blind our eyes in our present fallen state; but we may bless God for the light shining as in a dark place, to guide us until the Sun of Righteousness shall come, and we shall be made capable of seeing Him (2Pe 1:19; Re 22:4). The lamp is fed with the oil of the Spirit. The allusion is to the lamps and torches carried at night before an Eastern caravan.