tasya kāryaṁ na vidyate

yah-one who; tu-but; atma-ratih-takes pleasure; eva-certainly; syat-remains; atma-trptah-self-illuminated; ca-and; manavah-a man; atmani-in himself; eva-only; ca-and; santustah-perfectly satiated; tasya-his; karyam-duty; na-does not; vidyate-exist.