Chasidut for Shabbat 44:13

Our sages z"l said "the lightening makes the mitzvah" (Shabbat 22b). This is to say that a person needs to become a flame (set oneself on fire, become ardent) in their service, and this is the lightening, and because the ardor can be for empty things, the tzadik only becomes ardent for holiness, and this is called resting since rest [ie setting] is called 'the vessel in which the love is inserted', that by the insertion of the love into the vessel there is resting of the love that rests upon the thing. And this is 'one who says resting [setting the candles] makes the mitzvah', that the lightening will insert love into the vessel, that will become ardent in its service, and this is what the true sages hinted at that the setting the candles is the character trait of kingship, that through this [one is] making the Creator king, by becoming ardent there is rest in the service to the Blessed Creator.