What is the meaning of "Ner l'Ragli Devarecha"?
Rashi: When I come to give a ruling, I look in the Torah, and it separates me from Isur, like a lamp saves a person from [falling] in pits.
Radak: When one walks in darkness, if he has a lamp he will not stumble on his path. So I do not stumble in my deeds and ways, for Your words are like a lamp. They make me careful not to sin.
Malbim: One who walks on the road needs a great light that illuminates from afar, so he will see the path on which to go. He also needs a small lamp near his foot, lest he step on thorns or obstacles. Your word is a lamp, lest I stumble on an obstacle in Derech Hashem, e.g. learning in order to quarrel, being haughty about giving rulings... It is also a great light to show to him the path, lest he err [and go on] paths of death.
Why does it mention both a lamp and light?
Shocher Tov 27: David says, when I begin Divrei Torah, they flow, and when I enter them, many gates are opened for me. Mishnas R. Aharon 4 p.36-37 - when I begin, the light is small, like a lamp. Later, there is great light.
