Bhagavad Gita
4.42

तस्मादज्ञानसम्भूतं हृत्स्थं ज्ञानासिनात्मनः | छित्त्वैनं संशयं योगमातिष्ठोत्तिष्ठ भारत ||४२||

tasmād ajñāna-sambhūtaṁ hṛt-sthaṁ jñānāsinātmanaḥ chhittvainaṁ saṁśhayaṁ yogam ātiṣhṭhottiṣhṭha bhārata

Translation

Therefore the doubts which have arisen in your heart out of ignorance should be slashed by the weapon of knowledge. Armed with yoga, O Bharata, stand and fight.

Interpretation

The powerful conclusion of Chapter 4: take the sword of knowledge ('jñānāsinā' — with the sword of wisdom) and cut through the doubt that sits in your heart, born of ignorance. Then take your stand in yoga (equanimity in action) and arise to fight. The external battle is resumed — but now informed by the deepest wisdom.