In chapter nine of the Bhagavad Gita, Shri Krishna initiates the dialogue by stating that the mind centered upon the Lord is the one that attains Liberation. He goes on to enumerate the methods through which it can be achieved.

Dwelling on the relationship between the manifest (gross) and the unmanifest (subtle), he draws out our essential nature as that of supreme Brahman.

Commentary on All Chapters of Shrimad Bhagavad Gita, available as a pack.