Bhagavad Gita Chapter 5.20
na prahṛṣyet priyaḿ prāpya
nodvijet prāpya cāpriyam
sthira-buddhir asammūḍho
brahma-vid brahmaṇi sthitaḥ
Translation
A person who neither rejoices upon achieving something pleasant nor laments upon obtaining something unpleasant, who is self-intelligent, who is unbewildered, and who knows the science of God, is already situated in transcendence.