Bhagavad Gita · Sankhya YogaChapter 2, Shloka 49 (2.49)

"Buddhi-yoga" — the yoga of understanding. Shankaracharya: action joined with even-minded understanding. Ramanuja: the buddhi-yoga in which there is giving up of the main fruit (heaven and the like) and evenness in the success or failure of the intermediate fruit (victory and the like).

A great difference between two kinds of action. From the outside, both actions may look the same — the same battle, the same work. The difference lies in the buddhi (the understanding within). Ramanuja: action joined with buddhi-yoga removes all worldly suffering and gives moksha; the other kind of action gives samsara, which is boundless suffering.

"Kṛpaṇāḥ phala-hetavaḥ" — those who act for the fruit are pitiable. Here Shankaracharya quotes the Brihadaranyaka Upanishad (3.8.10): "yo vā etad akṣaraṃ gārgy aviditvā asmāl lokāt praiti sa kṛpaṇaḥ" — "O Gargi, one who departs from this world without knowing this imperishable is a kripana (pitiable)." This is the same "kripana" that Arjuna had used of himself in 2.7 (kārpaṇya-doṣa).

"Buddhau śaraṇam anviccha" — take refuge in understanding. Ramanuja: śaraṇa = vāsa-sthāna — dwell in this very understanding. Shankaracharya: take refuge in the understanding of yoga, or in the understanding of sankhya that ripens from it — make knowledge of the highest truth your support.