Bhagavad Gita 1.37

तस्मान्नारहा वयं हन्तुं धार्तराष्ट्रानस्वबन्धवान् |
स्वजनं हि कथं हत्वा सुखिन: स्याम माधव

Translation

Hence, it does not behoove us to kill our own cousins, the sons of Dhritarashtra, and friends. O Madhav (Krishna), how can we hope to be happy by killing our own kinsmen?