He whose happiness is internal, whose delight is internal, and whose light is internal, that yogī, made Brahman, reaches extinction in Brahman.

Internal as completeness. Antaḥ-sukhaḥ — of internal happiness — does not depend on external circumstances.

Antar-ārāmaḥ — of internal delight — finds pleasure in meditation, not in objects. Antar-jyotiḥ — of internal light — is self-illuminated, does not seek external light. Result: brahma-bhūtaḥ — made Brahman, transformed into Brahman — adhigacchati — reaches — brahma-nirvāṇam — extinction in Brahman, cessation of individuality in Unity.