Bhagavad Gita Chapter 5.24
yo ’ntaḥ-sukho ’ntar-ārāmas
tathāntar-jyotir eva yaḥ
sa yogī brahma-nirvāṇaḿ
brahma-bhūto ’dhigacchati
Translation
One whose happiness is within, who is active and rejoices within, and whose aim is inward is actually the perfect mystic. He is liberated in the Supreme, and ultimately he attains the Supreme.