5.11

कायेन मनसा बुद्ध्या केवलैरिन्द्रियैरपि ।
योगिनः कर्म कुर्वन्ति सङ्गं त्यक्त्वात्मशुद्धये ॥

kāyena manasā buddhyā kevalair indriyair api
yoginaḥ karma kurvanti saṅgaṃ tyaktvātmaśuddhaye

Kṛṣṇa (कृष्ण) continues. The one man of 5.10 becomes the yoginaḥ (योगिनः), and the instruments of their action are named.

The verse

Yogins do action with the body, the mind, the intellect, and the senses alone, having left attachment, for the cleansing of the self.

नेपालीमा

योगीहरू केवल शरीर, मन, बुद्धि र इन्द्रियले, आसक्ति छाडेर, आत्माको शुद्धिका लागि कर्म गर्छन्।

Where it sits

The acts of 5.8 and 5.9 are picked up again as instruments, and they are given a purpose. The purpose is the cleaning of the self. It is not a fruit waiting at the end of the battle. 5.12 will say what happens to the man who still wants the fruit.

Split: कायेन + मनसा + बुद्ध्या + केवलैः + इन्द्रियैः + अपि + योगिनः + कर्म + कुर्वन्ति + सङ्गम् + त्यक्त्वा + आत्म-शुद्धये

kāyena + manasā + buddhyā + kevalaiḥ + indriyaiḥ + api + yoginaḥ + karma + kurvanti + saṅgam + tyaktvā + ātma-śuddhaye

Sanskrit, in depth

The words

देवनागरीWordGrammarSense
कायेनkāyenainstrumental singularwith the body.
मनसाmanasāinstrumental singular of manas (मनस्)with the mind.
बुद्ध्याbuddhyāinstrumental singular of buddhi (बुद्धि)with the intellect.
केवलैःkevalaiḥinstrumental pluralwith mere. Alone.
इन्द्रियैःindriyaiḥinstrumental pluralwith the senses.
अपिapiindeclinablealso.
योगिनःyoginaḥnominative plural of yogin (योगिन्)yogins.
कर्मkarmaaccusative singular of karman (कर्मन्)action.
कुर्वन्तिkurvantipresent, 3rd pluralthey do.
सङ्गम्saṅgamaccusative singularattachment.
त्यक्त्वाtyaktvāgerundhaving left.
आत्म-शुद्धयेātma-śuddhayedative singularfor the cleansing of the self.

The phrases

kāyena manasā buddhyā (कायेन मनसा बुद्ध्या) are three instruments: body, mind, intellect. kevalaiḥ indriyaiḥ api (केवलैः इन्द्रियैः अपि) adds a fourth, the senses by themselves. kevalaiḥ (केवलैः) agrees with indriyaiḥ (इन्द्रियैः). The senses too, and only the senses, with no extra claim attached.

yoginaḥ karma kurvanti (योगिनः कर्म कुर्वन्ति) is the main clause. They do action. saṅgam tyaktvā (सङ्गम् त्यक्त्वा) is the same leaving as in 5.10. ātmaśuddhaye (आत्मशुद्धये) is what the action is for.

kevalaiḥ indriyaiḥ api (केवलैः इन्द्रियैः अपि) is recited kevalair indriyair api (केवलैरिन्द्रियैरपि). tyaktvā ātmaśuddhaye (त्यक्त्वा आत्मशुद्धये) is recited tyaktvātmaśuddhaye (त्यक्त्वात्मशुद्धये).

Sanskrit in this line

ātmaśuddhaye (आत्मशुद्धये) is dative singular. The dative answers "for." śuddhaye (शुद्धये) is "for cleansing," and ātma (आत्म) at the front says whose cleansing. The instruments are "with." The purpose is "for." The verse keeps them in different cases so the body is not mistaken for the goal.

Say it back

List the instruments, then the purpose. If ātmaśuddhaye (आत्मशुद्धये) comes out as "by the self," the dative has been heard as an instrumental. Stay here.