brahmabhootaha prasannaatmaa nashochati na kaankshati |
samaha sarveshu bhooteshu madbhaktim labhate paraam || 54 ||

One who has become the eternal essence, who has attained the joyful self, does not grieve nor desire. Equanimous towards all beings, he attains supreme devotion to me.
brahmabhootaha : one who has become the eternal essence
prasannaatmaa : attained the joyful self
na : not
shochati : grieve
na : not
kaankshati : desire
samaha : equanimous
sarveshu : towards all
bhooteshu : beings
madbhaktim : devotion to me
labhate : attains
paraam : supreme
Having described the duties of a monk or a sanyaasi in the previous three shlokas, Shri Krishna explains the result of assiduously following those duties. The monk develops supreme devotion, paraa bhakti, towards Ishvara. As the monk decreases his involvement in the material world, makes his mind pure, his devotion towards Ishvara starts to increase. The culmination of this devotion is complete equanimity towards everyone and everything. He sees everyone’s joy as his joy, and everyone’s sorrow as his sorrow. He feels fulfilled in himself, therefore he has no desire for anything new, or no grief for anything that he does not have. Only joy remains.
From the standpoint of Vedanta, the first six chapters of the Gita covered the analysis of “tvam”, the individual. Starting with karma yoga, then the purification of mind, then the study of scriptures, followed by taking up renunciation of all actions or monkhood, the seeker comes to know himself as the pure self, as distinct from his body and mind, which are products of maaya. But so long as he sees even a tinge of difference between his self and the world, that tinge of difference will eventually bring back raaga and dvesha, like and dislike. Therefore, he also needs to conduct analysis on the “tat”, which is Ishvara.
Analysis of Ishvara, knowing Ishvara in essence, was the topic of the chapters seven to twelve in the Gita. The seeker realizes that Ishvara creates, supports and destroys the world, through his power known as maaya. Maaya has the power to cover the true nature of Ishvara, and project a world of dazzling name and form. But, by listing Ishvara’s vibhootis, and by eventually describing his universal form, Shri Krishna informs the seeker that Ishvara also, like the self, is distinct from the universal body and the universal mind. All that the seeker needs to do is to see the oneness between his pure self and Ishvara’s pure self, distinct from all effects of maaya.