Bhagavad Gita · Jnana Karma Sannyasa YogaChapter 4, Shloka 42 (4.42)

Three steps. (1) Recognise the doubt — ajñāna-sambhūta, hṛt-stha (born of ignorance, seated in the heart); (2) cut it with the sword of knowledge; (3) yogam ātiṣṭha, uttiṣṭha (take your stand in yoga, arise).

Shankaracharya: pāpiṣṭham ajñāna-sambhūtam … hṛdi buddhau sthitam — the worst evil, born of ignorance (lack of discernment), seated in the heart, that is, in the buddhi; jñānāsinā śoka-mohādi-doṣa-haraṃ samyag-darśanaṃ jñānaṃ tad eva asiḥ — right vision, which removes the faults of grief, delusion and the like, is itself the sword. Ātmanaḥ — because the doubt concerns one's own self, it is one's own — na hi parasya saṃśayaḥ pareṇa chettavyatāṃ prāptaḥ — no one else cuts away another's doubt. Yogaṃ samyag-darśanopāyaṃ karmānuṣṭhānam ātiṣṭha — take your stand in yoga, the means to right vision, the performance of action (karma-yoga); uttiṣṭha ca idānīṃ yuddhāya — and now arise to fight. (The end of Shankara's commentary on the fourth chapter.)

Acharya Ramanuja: anādy-ajñāna-sambhūtaṃ hṛt-stham ātma-viṣayaṃ saṃśayam — the doubt about the self, born of beginningless ignorance and sitting in the heart, mayā upadiṣṭena ātma-jñānāsinā chittvā — cutting it with the sword of knowledge of the self that I have taught, mayā upadiṣṭaṃ karma-yogam ātiṣṭha, tad-artham uttiṣṭha — take your stand in the karma-yoga I have taught, and arise for it.