BG 2.38-40
Taking as equal pleasure and pain, gain and loss, victory and defeat, gird thee for the battle; thus thou shalt not incur sin. This teaching set forth to thee is in accordance with the Sâñkhya; hear it now according to the Yoga, imbued with which teaching, O Pârtha, thou shalt cast away the bonds of action. In this there is no loss of effort, nor is there transgression. Even a little of this knowledge protects from great fear.