B.G 3.18

नैव तस्य कृतेनार्थो नाकृतेनेह कश्चन। न चास्य सर्वभूतेषु कश्चिदर्थव्यपाश्रयः ॥१८॥

naiva tasya kr̥tēnārthō nākr̥tēnēha kaścana। na cāsya sarvabhūtēṣu kaścidarthavyapāśrayaḥ ॥18॥

[न एव तस्य कृतेन अर्थो न अकृतेन इह कश्चन। न च अस्य सर्वभूतेषु कश्चित् अर्थ व्यपाश्रयः॥
na = not; ēva = alone; tasya = his; kr̥tēna = by performance of duties; arthō = wellbeing/ purpose; na = not; akr̥tēna = non-performance of duties; iha = in this world; kaścana = whatever; na =not; ca = and; asya = for this; sarvabhūtēṣu = in all beings; kaścit = any; artha vyapāśrayaḥ = the wellbeing by which the direct vision becomes possible; ]

For such a person (in a deep meditative state), there is no purpose to be served by performance of duties enjoined, nor any sin results from failure to perform them. Nor, in the entire range of creation, can there be anything which further enables his direct vision.

Gīta Bhāshya 3.18

The person indicated here is the one in a deep meditative state and not a knowledgeable person (jnānin) in general. 'arthavyapāśraya' - "the wellbeing by which the direct vision becomes possible"

[Sankara Bhasya (translated by A.M. Sastry):
For the man thus rejoicing in the Self, no purpose is served by action.- Does, then, any evil called sin (pratyavaya) arise from inaction? - No evil whatever, either by way of incurring sin, or by way of losing the Self, arises in this world from inaction. Nor is there, in all beings from Brahma (Prajapati) down to the sthavara i.e. immovable objects, any whose support be has to gain by action. He has no object whatever to gain, for which he has to depend upon any particular being: if he were to have any object in view, then he would have to exert himself to gain that object.
You have not attained to the right knowledge, which corresponds to the all-spreading flood of water (vide ii. 46). Wherefore:]

तस्य 'कर्मकाले वक्तव्योऽहम्' इति कञ्चित् प्रत्युक्त्वा तत्कृतौ आत्मरत्यधिकः समो वा अर्थः नास्ति। न च सन्ध्याद्यकृतौ कश्चिद्दोषः अस्ति। न च एतदपहाय सर्वभूतेषु कश्चित् प्रयोजनाश्रयः। अर्थः येन दर्शनादिना भवति सः अर्थव्यपाश्रयः।

tasya 'karmakālē vaktavyō'ham' iti kañcit pratyuktvā tatkr̥tau ātmaratyadhikaḥ samō vā arthaḥ nāsti। na ca sandhyādyakr̥tau kaściddōṣaḥ asti। na ca ētadapahāya sarvabhūtēṣu kaścit prayōjanāśrayaḥ। arthaḥ yēna darśanādinā bhavati saḥ arthavyapāśrayaḥ।

[tasya = him who is in deep meditation; karmakālē = at the time when my duty is due; vaktavyō'ham = inform me; iti = thus; kañcit = somewhat; pratyuktvā = to ask others; tatkr̥tau = in that action; ātmaratyadhikaḥ = more happiness; samō = equal; vā = or; arthaḥ = it makes sense; nāsti = not;। na = nor; ca = and; sandhyādyakr̥tau = in doing evenining worship; kaściddōṣaḥ = any defect; asti = exist;। na = not; ca = and; ētadapahāya = this, without giving up; sarvabhūtēṣu = in all beings; kaścit = any; prayōjanāśrayaḥ = purpose is sheltered; arthaḥ = The well being; yēna = by which; darśanādinā bhavati = the direct vision becomes possible; saḥ = that is ; arthavyapāśrayaḥ = 'arthavyapāśraya';]

For a person in deep meditation, it does not make sense to ask others, "wake me up and inform", when the time of duty arrives, as it will not provide greater or equal happiness. And, by not doing evening worship, no defects arise (as the person is in deep meditation). Nor does any purpose gets served among all beings by giving up such a meditation. The word 'arthavyapāśraya' means "the wellbeing by which the direct vision becomes possible".

ज्ञानमात्रेण यद्यपि प्रत्यवायो न भवति। तदर्जुनस्यापि समं इति न तस्य कर्मोपदेशोपयोगि एतद् भवति। ईषत् प्रारब्धानर्थसूचकं च तद्भवति। महच्चेद् वृत्रहत्यादिवत् ॥१८॥

jñānamātrēṇa yadyapi pratyavāyō na bhavati। tadarjunasyāpi samaṁ iti na tasya karmōpadēśōpayōgi ētad bhavati। īṣat prārabdhānarthasūcakaṁ ca tadbhavati। mahaccēd vr̥trahatyādivat ॥18॥

[jñānamātrēṇa = by knowledge alone; yadyapi = if, it; pratyavāyō = impediment; na = not; bhavati = happens; tadarjunasyāpi = for Arjuna also; samaṁ = the same; iti = thus; na = not; tasya = his; karmōpadēśōpayōgi = having the use or utility of advice on action; ētad = this; bhavati = becomes; īṣat = a little; prārabdhānarthasūcakaṁ = the pending karma (prārabdh) is indicative of sins; ca = and; tadbhavati = is bound to happen; mahaccēd vr̥trahatyādivat ॥18॥]

If by knowledge alone impediments are removed, then for Arjuna also it should happen without resorting to the advice on action. Even the little of pending imprints because of sins is bound to unwind. If it is great, then scenarios like "killing of Vrutrasura daemon".