Bhagavad Gita Chapter 2.56
duḥkheṣv anudvigna-manāḥ
sukheṣu vigata-spṛhaḥ
vīta-rāga-bhaya-krodhaḥ
sthita-dhīr munir ucyate
Translation
One who is not disturbed in mind even amidst the threefold miseries or elated when there is happiness, and who is free from attachment, fear and anger, is called a sage of steady mind.