Just as a blazing fire turns firewood to ashes, O Arjuna, so the fire of knowledge turns all actions to ashes.
Explanation
Krishna continues telling Arjuna about the power of knowledge (jñāna), using the image of a fire reducing wood to ash. Knowledge here burns away the binding effects of actions (karma), meaning the bonds of past deeds and the pull of results. Traditions differ on what this knowledge is: Advaita readings take it as knowledge of the Self, while devotional and yoga-centered readings stress knowledge joined with selfless action or devotion.