Bhagavad Gita · Karma YogaChapter 3, Shloka 4 (3.4)

Two wrong paths.

1. Anārambha — not starting action at all.
2. Sannyasana maatra — simply abandoning action already begun (without inner preparation).

Neither brings naiṣkarmya/siddhi.

Shankaracharya — action itself is the means. Actions destroy sin (from this birth or earlier births) and bring sattva-śuddhi (purification of the inner being); from that knowledge arises, and from knowledge, steadfastness in knowledge. Na hy upāyam antareṇa upeya-prāptir asti — without the means, the goal is not reached. He quotes the Brihadaranyaka (4.4.22) — tam etaṃ vedānuvacanena brāhmaṇā vividiṣanti yajñena… — through study of the Vedas and through yajña, people seek to know it. He also quotes 5.6, 5.11 and 18.5 from the Gita. The second half of the verse — no perfection through renunciation alone — means for Shankara: renunciation without knowledge.

Acharya Ramanuja: By not undertaking the actions prescribed by scripture, one does not attain jnana-nishtha; nor by abandoning scriptural actions once begun — because steadfastness in the self is itself the fulfilment of action done without desire for fruit, as worship of the Lord. Without such action, the store of sins accumulated from beginningless time is not destroyed, and steadfastness in the self, which rests on the calming of the senses, is duḥsampādyā — hard to achieve.