Oil -- typically olive oil -- symbolizes the good that comes from celestial love. Celestial love is love of the Lord, the highest and purest love we can have. The good of celestial love is the desire to be good springing from celestial love: Wanting to do the Lord's will because you love Him. That's not a state many reach, even in heaven, but it's a beautiful goal. This representation makes sense based on the idea that the sun -- the source of all natural light and heat, and thus all natural life -- represents the Lord, the source of all spiritual light, heat and life. Burning oil was the most pure fire available in Biblical times, thus the closest representation of the sun people could create.

9314. 'And will act as adversary to your adversaries' means that He will turn away all evils from which falsities arise. This is clear from the meaning of 'acting as adversary', when it refers to Jehovah or the Lord, as turning away, dealt with immediately above in 9313; and from the meaning of 'adversaries' as evils from which falsities arise, since those evils in the spiritual sense are 'adversaries' opposed to forms of good from which truths spring. The reason why evils from which falsities arise are meant by 'adversaries' is that falsities arising from evil are meant by 'enemies'; for wherever falsity is the subject in the Word, so too is evil, even as when truth is the subject so too is good, see 683, 793, 801, 2173, 2516, 2712, 3132, 4138 (end), 5138, 5502, 6343, 7945, 8339. From this it is evident that one thing is meant by 'acting as enemy to enemies' and another thing by 'acting as adversary to adversaries', and that the latter is not a repetition that occurs simply to make the subject sound more lofty.