Bhagavad Gita Chapter 2.48
yoga-sthaḥ kuru karmāṇi
sańgaḿ tyaktvā dhanañjaya
siddhy-asiddhyoḥ samo bhūtvā
samatvaḿ yoga ucyate
Translation
Perform your duty equipoised, O Arjuna, abandoning all attachment to success or failure. Such equanimity is called yoga.