In plain words
This world is bound by action except when action is performed for the sake of yajña. Therefore, son of Kunti, perform action for that sake, free from attachment.
Word for word
Other than action done for the sake of yajña, this world is bound by action; for that sake, O son of Kuntī, free from attachment, perform action.
यज्ञार्थात् कर्मणोऽन्यत्र लोकोऽयं कर्मबन्धनःतदर्थं कर्म कौन्तेय मुक्तसङ्गः समाचर
Other commentaries
The commentators
▸Bhagavadgītābhāṣyam
यच्च मन्यसे बन्धार्थत्वात् कर्म न कर्तव्यमिति तदप्यसत् । कथम् —
‘यज्ञो वै विष्णुः’(तै. स. १ । ७ । ४) इति श्रुतेः यज्ञः ईश्वरः, तदर्थं यत् क्रियते तत् यज्ञार्थं कर्म । तस्मात् कर्मणः अन्यत्र अन्येन कर्मणा लोकः अयम् अधिकृतः कर्मकृत् कर्मबन्धनः कर्म बन्धनं यस्य सोऽयं कर्मबन्धनः लोकः, न तु यज्ञार्थात् । अतः तदर्थं यज्ञार्थं कर्म कौन्तेय, मुक्तसङ्गः कर्मफलसङ्गवर्जितः सन् समाचर निर्वर्तय ॥ ९ ॥
In plain words
And that other thing you think — that action isn't to be done at all, since action only binds — that too is baseless. How so? —
'Sacrifice, indeed, is Viṣṇu' — this is what the Taittirīya Saṃhitā (1.7.4) tells us, and so sacrifice really means the Lord himself. Whatever is done for his sake, that is action done for the sake of sacrifice. Any other kind of action, apart from that, is what binds this world — this world so bent on action and so entitled to it — action becomes its very bond, and that is exactly what 'bound by action' means. But action done for the sake of sacrifice is not like that. So act, Kaunteya, but act only for that purpose — for the sake of sacrifice — free of attachment, free even of attachment to what your action produces. Perform it, and let it be done.
Close to the Sanskrit
And that which you think — 'action is not to be done, because of its having bondage as its result' — that too is untrue. How? —
'Sacrifice, indeed, [is] Viṣṇu' (Taittirīya Saṃhitā 1.7.4) — because of this scriptural statement, sacrifice [is] the Lord; that which is done for his sake, that [is] action for the sake of sacrifice. Other than from that action, by another action, this world — [i.e.] this entitled, action-performing [world] — [is] bound by action — [i.e.] one for whom action is the bond, that is this world 'bound by action' — but not from action for the sake of sacrifice. Therefore, for that purpose — for the purpose of sacrifice — [perform] action, O Kaunteya, being free from attachment, devoid of attachment to the fruit of action; perform, carry out.