sāṃkhyayoga - Verse śloka 38
śloka 38
sukhaduḥkhe same kṛtvā lābhālābhau jayājayau |
tato yuddhāya yujyasva naivaṃ pāpamavāpsyasi ||2-38||
Translation
Treating pleasure and pain, gain and loss, victory and defeat as equal, prepare yourself for battle; thus you will incur no sin.