4.21

निराशीर्यतचित्तात्मा त्यक्तसर्वपरिग्रहः ।
शारीरं केवलं कर्म कुर्वन्नाप्नोति किल्बिषम् ॥

nirāśīr yatacittātmā tyaktasarvaparigrahaḥ
śārīraṃ kevalaṃ karma kurvannāpnoti kilbiṣam

Kṛṣṇa (कृष्ण) is still speaking, to Arjuna.

The verse

Without expectation, mind and self held, every grasping dropped, he does not obtain a stain while doing mere bodily action.

नेपालीमा

आशारहित, मन र आत्मा वशमा, सबै ग्रहण छाडेर, केवल शरीरको कर्म गर्दा पनि उसले दाग पाउँदैन।

Where it sits

4.20 said the engaged man does nothing at all, and this verse says the remaining action is only the body's, and it leaves no stain. 4.22 will add success and failure, and still no binding.

Split: निराशीः + यत-चित्त-आत्मा + त्यक्त-सर्व-परिग्रहः + शारीरम् + केवलम् + कर्म + कुर्वन् + न + आप्नोति + किल्बिषम्

nirāśīḥ + yata-citta-ātmā + tyakta-sarva-parigrahaḥ + śārīram + kevalam + karma + kurvan + na + āpnoti + kilbiṣam

Sanskrit, in depth

The words

देवनागरीWordGrammarSense
निराशीःnirāśīḥnominative of nirāśis (निराशिस्)one whose expectation has gone. āśis (आशिस्) is a wish, a hope set on a result.
यत-चित्त-आत्माyata-citta-ātmānominative, bahuvrīhi (बहुव्रीहि)one whose mind and self are held. yata (यत) is "restrained," from yam (यम्).
त्यक्त-सर्व-परिग्रहःtyakta-sarva-parigrahaḥnominative, bahuvrīhi (बहुव्रीहि)one who has dropped every grasping. parigraha (परिग्रह) is taking, possessing.
शारीरम्śārīramaccusative neuterbodily. Belonging to the body. Agrees with karma (कर्म).
केवलम्kevalamaccusative neutermere, only.
कर्मkarmaaccusativeaction.
कुर्वन्kurvanpresent participle, nominativedoing.
नnaindeclinablenot. Hidden in the join kurvannāpnoti (कुर्वन्नाप्नोति).
आप्नोतिāpnotipresent, 3rd singularhe obtains. From āp (आप्).
किल्बिषम्kilbiṣamaccusativea stain, a fault.

The phrases

nirāśīḥ yatacittātmā tyaktasarvaparigrahaḥ (निराशीः यतचित्तात्मा त्यक्तसर्वपरिग्रहः) is the man, in three nominatives. Without expectation, mind and self held, every grasping dropped. nirāśīḥ (निराशीः) before y (य्) is nirāśīr (निराशीर्): nirāśīr yatacittātmā (निराशीर्यतचित्तात्मा).

śārīraṃ kevalaṃ karma kurvan na āpnoti kilbiṣam (शारीरं केवलं कर्म कुर्वन् न आप्नोति किल्बिषम्) is the doing that remains, and what it does not bring. Doing merely bodily action, he does not obtain a stain. न + आप्नोति na + āpnoti is nāpnoti (नाप्नोति). kurvan (कुर्वन्) before that n (न्) doubles it: kurvannāpnoti (कुर्वन्नाप्नोति). The recited run is one piece, kurvannāpnoti (कुर्वन्नाप्नोति). śārīram (शारीरम्) and kevalam (केवलम्) both describe karma (कर्म). The action is the body's, and it is only that.

Sanskrit in this line

kurvannāpnoti (कुर्वन्नाप्नोति) divides as कुर्वन् + न + आप्नोति kurvan + na + āpnoti. न + आ na + ā makes the long ā (आ), and the two n (न्) sounds meet. The same letters can be taken as the doubled n (न्) of 4.6 with no negative, कुर्वन् + आप्नोति kurvan + āpnoti, which would say he does obtain the stain. This sitting keeps the na (न). The man of 4.20 does nothing at all.

Say it back

What kind of action, and what he does not obtain. If the na (न) inside kurvannāpnoti (कुर्वन्नाप्नोति) is not said, stay here.