Verse 18

आपतत्सु यथाकालं सुखदुःखेष्वनारतम् ।न हृष्यति ग्लायति यः स मुक्त इति होच्यते

In plain words

Amid pleasures and pains that come, one after another, as time brings them, he who neither exults nor languishes -- he indeed is called liberated.