Bhagavad Gita Verse 27, Chapter 14

brahmano hi pratishthaahamamritasyaavyayasya cha |
shaashvatasya cha dharmasya sukhasyaikaantikasya cha || 27 ||
 
For, I am the abode of brahman, the immortal, the imperishable, the eternal constitution, and of absolute joy.
 
brahmanaha : brahman
hi : for
pratishthaa : abode
aham : I am
amritasya : immortal
avyayasya : imperishable
cha : and
shaashvatasya : eternal
cha : and
dharmasya : constitution
sukhasya : of joy
aikaantikasya : absolute
cha : and
 
The thirteenth chapter of the Gita explained the topic of jnyaana yoga or the yoga of knowledge. One of the topics in that chapter was the description of nirguna brahman, which is the eternal essence in its purest state. Shri Krishna described the technique of mentally removing the upaadhis - the veiling of the organs, the senses and so on - to get to the eternal essence that is at the core all of us. One who attained this eternal essence through jnyaana yoga achieved liberation or moksha. Arjuna recollected this teaching, and a doubt arose in his mind. What was that doubt?
 
In the previous shloka of this chapter, Shri Krishna asserted that liberation would be attained by the one who has undivided devotion towards Ishvara. But in the previous chapter, Shri Krishna had said that the fruit of knowing the eternal essence in its purest state, nirguna brahman, also resulted in liberation. To address Arjuna's doubt about the difference between the two approaches, Shri Krishna says here that he, as Ishvara, is the abode of the pure eternal essence, of nirguna brahman. In other words, undivided devotion to Ishvara results in the same outcome as does the yoga of knowledge. He also describes this pure eternal essence as immortal, imperishable, eternal and full of joy, just like he did in the thirteenth chapter. Furthermore, he says that the eternal essence is attained through the dharma or constitution of devotion and knowledge.
 
Shri Shankaraachaarya provides further nuances to this explanation in his commentary. He says that Prakriti or maaya is a power of nirguna brahman. Just like the strength of a strong person is inseparable from the person itself, maaya is inseparable from nirguna brahman. Therefore, it is nirguna brahman, with the power of maaya, that is speaking to Arjuna as Ishvara. This is the connection between nirguna brahman - brahman without maaya - and saguna brahman - brahman with maaya. Saguna brahman is the abode, and the power, of nirguna brahman. And the methods to attain brahman - devotion and knowledge - are two sides of the same coin. With this message, Shri Krishna concludes the fourteenth chapter.
 
om tatsatiti shreematbhagavatgitasupanishadsu brahmavidyaayaam yogashaastre shreekrishnaarjunsamvade gunatrayavibhaagayogo naama chaturdashodhyaayaha || 14 ||