BG Chap 18 - Even though it is Arjuna's nature to fight, Kṛṣṇa pushed him because ...

Kṛṣṇa wanted Arjuna to fight in proper consciousness. Therefore He told Arjuna to surrender unto Him and fight on His order with devotion. Kṛṣṇa doesn’t require Arjuna’s skills to gain victory as the battle was already won by Kṛṣṇa. But He wanted Arjuna to act with devotion as His instrument. Arjuna’s devotion will be expressed by fighting on the battlefield. If one refuses to act under the direction of the Supreme Lord, then he is compelled to act by the modes in which he is situated. Everyone is under the spell of a particular combination of the modes of nature and is acting in that way. The surrendered souls are controlled and protected by Kṛṣṇa, and the un-surrendered souls are controlled by māyā. But anyone who voluntarily engages himself under the direction of the Supreme Lord becomes glorious.