Bhagavad Gita Chapter 13.19
iti kṣetraḿ tathā jñānaḿ
jñeyaḿ coktaḿ samāsataḥ
mad-bhakta etad vijñāya
mad-bhāvāyopapadyate
Translation
Thus the field of activities [the body], knowledge and the knowable have been summarily described by Me. Only My devotees can understand this thoroughly and thus attain to My nature.