Text 37-38

यद्यप्येते न पश्यन्ति लोभोपहतचेतसः ।
कुलक्षयकृतं दोषं मित्रद्रोहे च पातकम् ॥३७॥
कथं न ज्ञेयमस्माभिः पापादस्मान्निवर्तितुम् ।
कुलक्षयकृतं दोषं प्रपश्यद्भिर्जनार्दन ॥३८॥

yady apy ete na paśyanti
lobhopahata-cetasaḥ
kula-kṣaya-kṛtaḿ doṣaḿ
mitra-drohe ca pātakam
kathaḿ na jñeyam asmābhiḥ
pāpād asmān nivartitum
kula-kṣaya-kṛtaḿ doṣaḿ
prapaśyadbhir janārdana

Translation:

O Janardana, although these men, their hearts overtaken by greed, see no fault in killing one's family or quarreling with friends, why should we, who can see the crime in destroying a family, engage in these acts of sin?

Purport:

A kshatriya is not supposed to refuse to battle or gamble when he is so invited by some rival party. Under such an obligation, Arjuna could not refuse to fight, because he had been challenged by the party of Duryodhana. In this connection, Arjuna considered that the other party might be blind to the effects of such a challenge. Arjuna, however, could see the evil consequences and could not accept the challenge. Obligation is actually binding when the effect is good, but when the effect is otherwise, then no one can be bound. Considering all these pros and cons, Arjuna decided not to fight.