nihatya dhārtarāṣhṭrān naḥ kā prītiḥ syāj janārdana
pāpam evāśhrayed asmān hatvaitān ātatāyinaḥ||36||

tasmān nārhā vayaṁ hantuṁ dhārtarāṣhṭrān sa-bāndhavān
sva-janaṁ hi kathaṁ hatvā sukhinaḥ syāma mādhava||37||

Meaning : What joy would we gain, O Janardana (Krishna), by killing the sons of Dhritarashtra? Killing these aggressors would only make us sinners.
Therefore, we should not kill the sons of Dhritarashtra along with their family and friends. How could we ever be happy after killing our own people, O Madhava?