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yoga-sthaḥ kuru karmāṇi saṅgaṁ tyaktvā dhanañjaya
siddhy-asiddhyoḥ samo bhūtvā samatvaṁ yoga uchyate
Be steadfast in the performance of your duty, O Arjun, abandoning attachment to success and failure. Such equanimity is called Yog.
Word by Word Meaning:
yoga-sthaḥ - being steadfast in yog
kuru - perform
karmāṇi - duties
saṅgam - attachment
tyaktvā - having abandoned
dhanañjaya - Arjun
siddhi-asiddhyoḥ - in success and failure
samaḥ - equipoised
bhūtvā - becoming
samatvam - equanimity
yogaḥ - Yog
uchyate - is called