स्वधर्ममपि चावेक्ष्य न विकम्पितुमर्हसिधर्म्याद्धि युद्धाच्छ्रेयोऽन्यत् क्षत्रियस्य न विद्यते
In plain words
Looking also to your own dharma, you should not waver. For a kṣatriya there is nothing higher than a battle undertaken for dharma.
Word for word
And looking also to your own dharma, you ought not to waver; for, than a battle in accord with dharma, no other good exists for a kṣatriya.
स्वधर्ममपि चावेक्ष्य न विकम्पितुमर्हसिधर्म्याद्धि युद्धाच्छ्रेयोऽन्यत् क्षत्रियस्य न विद्यते
Other commentaries
The commentators
▸Bhagavadgītābhāṣyam
इह परमार्थतत्त्वापेक्षायां शोको मोहो वा न सम्भवतीत्युक्तम् । न केवलं परमार्थतत्त्वापेक्षायामेव । किं तु —
स्वधर्ममपि स्वो धर्मः क्षत्रियस्य युद्धं तमपि अवेक्ष्य त्वं न विकम्पितुं प्रचलितुम् नार्हसि क्षत्रियस्य स्वाभाविकाद्धर्मात् आत्मस्वाभाव्यादित्यभिप्रायः । तच्च युद्धं पृथिवीजयद्वारेण धर्मार्थं प्रजारक्षणार्थं चेति धर्मादनपेतं परं धर्म्यम् । तस्मात् धर्म्यात् युद्धात् श्रेयः अन्यत् क्षत्रियस्य न विद्यते हि यस्मात् ॥ ३१ ॥
In plain words
What has been said so far is this: when you hold the ultimate truth in view, grief and confusion have no room to arise. And not only when you hold that ultimate truth in view. There is more —
Consider your own duty as well -- for a Kshatriya, that duty is to fight. Once you've truly looked at that, you have no business wavering or backing away from what's simply built into who you are by nature. And this particular war -- fought to secure the earth, in service of dharma, to protect the people -- doesn't step outside dharma at all; it's righteous through and through. Which is exactly why, for a warrior, nothing is better than a righteous war.
Close to the Sanskrit
Here, when the ultimate reality is what one has in view, grief or delusion does not arise — thus it has been said. Not only when the ultimate reality is what one has in view. But rather —
'Your own duty' too -- one's own duty for a Kshatriya is battle; that too, having considered, you should not waver [from], should not swerve from the Kshatriya's own natural duty -- 'from one's own inherent nature' is the purport. And that war, conducted by way of the conquest of the earth, for the sake of dharma and for the sake of protecting the people -- thus not deviating from dharma, is excellent, righteous. Therefore, for a Kshatriya, nothing better than righteous war exists, because [of this].