स्थितप्रज्ञस्य का भाषा समाधिस्थस्य केशव
स्थितधीः He who is steady in thought; both आसीत & व्रजेत are in the optative - 'how should he'?
केशव, समाधिस्थस्य स्थितप्रज्ञस्य का भाषा
स्थितधीः किम् प्रभाषेत किम् आसीत किम् व्रजेत
Now we'll go to Shri Krishna's (2:60) warning before the description:
(The) turbulent senses carry away the mind forcibly, Arjuna, even of the striving man of Wisdom.
यततो ह्यपि कौन्तेय पुरुषस्य विपश्चितः
Arjuna, indeed agitated/churned up senses carry away forcibly the mind (even) of the striving man.
यततः is an active present participle, and gives the sense of present continuous '-ing' -happening, doing, striving. In Sanskrit this is called the वर्तमाने कृदन्त
प्रमाथीनि is from√मथ् churned, whirled
विपश्चितः is from√विप् inwardly inspired, whose चित्त is inwardly inspired
2:55 The Blesses Lord spoke: When he abandons all desires emerging from the mind, Arjuna; And is contented in the self, by the Self, then he is said to be one whose Wisdom is steady.
प्रजहाति यदा कामान् सर्वान् पार्थ मनोगतान्
आत्मनि एव आत्मना तुष्टः स्थितप्रज्ञः तदा उच्यते
पार्थ यदा मनोगतान् सर्वान् कामान् प्रजहाति
आत्मना आत्मनि एव तुष्टः तदा स्थितप्रज्ञः उच्यते
We have to supply the 'asti' after तुष्टः the sentence comes together. but as you know, the asti is often assumed and dropped in verses.
When (a man) abandons of all the desires that arise from (his/the) heart; is happy/satisfied by his-self in his-self, then he is known as a sthita-prajña.
2:56 He whose mind is not agitated in misfortune, whose desire for pleasures has disappeared, whose passion, fear and anger have departed, And whose meditation is steady, is said to be a sage.
दुःखेष्वनुद्विग्नमनाः सुःखेषु विगतस्पृहः
Anvaya and vigraha is pretty much the same for this verse.
In sorrow, un-agitated mind, in happiness, (his) desires are gone, gone is passion/liking, anger, fear; He whose mind is steady, is called muni.
2:57 He who is without attachment on all sides, encountering this or that, pleasant or unpleasant, neither rejoicing nor disliking, his Wisdom stands firm.
यः सर्वत्रानभिस्नेहः तत्तत् प्राप्य शुभाशुभम्
Vigraha and anvaya is practically the same for this verse also
यदा संहरते चायं कूर्मो Sङ्गानिव सर्वशः
And like a tortoise (who) withdraws its limbs from every direction, he who (withdraws) his senses from (the) sense objects, his Wisdom stands firm.