श्रेयान्स्वधर्मो विगुणः परधर्मात्स्वनुष्ठितात् | स्वभावनियतं कर्म कुर्वन्नाप्नोति किल्बिषम् ||१८-४७||
śreyānsvadharmo viguṇaḥ paradharmātsvanuṣṭhitāt . svabhāvaniyataṃ karma kurvannāpnoti kilbiṣam ||18-47||
Chapter 18 · Verse 47
Moksha Sannyasa Yoga
मोक्षसंन्यासयोग
In plain words
Just as a poisonous substance does not harm the worm born in that substance so he who does his Svadharma (the duty ordained according to his own nature) does not incur any sin. What is poison to the whole world is sweet to a worm and yet sugarcane juice that is sweet causes its death. So a mans appointed duty which frees him from bondage must therefore be practised however difficult it may seem to be.
Translation
18.47 Better is one's own duty, though ill done, than the duty of another, though well-performed৷৷৷৷৷৷ When one does the duty ordained by his own nature, he incurs no stain.
Meaning
Just as a poisonous substance does not harm the worm born in that substance so he who does his Svadharma (the duty ordained according to his own nature) does not incur any sin. What is poison to the whole world is sweet to a worm and yet sugarcane juice that is sweet causes its death. So a mans appointed duty which frees him from bondage must therefore be practised however difficult it may seem to be. If you try to do the duty of another it will bring,danger. He who has no knowledge of the Self cannot remain even for a moment without doing action. (Cf. III.35)
Word by word
श्रेयान् better स्वधर्मः ones own duty विगुणः (though) destitute of merits परधर्मात् that the duty of another स्वनुष्ठितात् (than) well performed स्वभावनियतम् ordained by his own nature कर्म action कुर्वन् doing न not आप्नोति (he) incurs किल्बिषम् sin.