3.17 Tu, but; that manavah, man, the sannyasin, the man of Knowledge, steadfast in the knowledge of the Self; yah, who; atmaratih eva syat, rejoices only in the Self-not in the sense objects; and atma-trptah, who is satisfied only with the Self-not with food and drink; and is santustah, contented; eva, only; atmani, in the Self; tasya, for him; na vidyate, there is no; karyam, duty [Duty with a view to securing Liberation.] to perform. [Rati, trpti and santosa, though synonymous, are used to indicate various types of pleasures. Or, rati means attachment to objects; trpti means happiness arising from contact with some particular object; and santosa means happiness in general, arising from the acisition of some coveted object only.]
All people surely feel contened by aciring an external thing. But this one, without depending on it, remains contented only with the Self; thta is to say, he remains detached from everything. The idea it that, for a man who is such a knower of the Self, there is no duty to undertake.