Section 2
Bhagavad-pitā As Jt Js
[Ch. 18]
ya idam paramam guhyam  
 mad-bhakteşv abhidhāsyati  
 bhaktim mayi parām kṛtvā  
 mām evaisyaty asaṁśayah
yaḥ —anyone;  idam —this;  paramam —most;  guhyam —confidential;  mat —Mine;  bhakteṣu —amongst devotees of;  abhidhāsyati —explains;  bhaktim —devotional service;  mayi —unto Me;  parām —transcendental;  kṛtvā —having done;  mām —unto Me;  eva —certainly;  eṣyati —comes;  asaṁśayaḥ —without doubt.
TRANSLATION
For one who explains the supreme secret to the devotees, devotional service is guaranteed, and at the end he will come back to Me.
PURPORT
Generally it is advised that  Bhagavad-gītā  be discussed amongst the devotees only, for those who are not devotees will neither understand Kṛṣṇa nor  Bhagavad-gītā . Those who do not accept Kṛṣṇa as He is and  Bhagavad-gītā  as it is should not try to explain  Bhagavad-gītā  whimsically and become offenders.  Bhagavad-gītā  should be explained to persons who are ready to accept Kṛṣṇa as the Supreme Personality of Godhead. It is a subject matter for the devotees only and not for philosophical speculators. Anyone, however, who tries sincerely to present  Bhagavad-gītā  as it is will advance in devotional activities and reach the pure devotional state of life. As a result of such pure devotion, he is sure to go back home, back to Godhead.
TEXT 69
न च तस्मान्मनुष्येषु कश्चिन्मे प्रियकृत्तमः । भविता न च मे तस्मादन्यः प्रियतरो भुवि ॥६९॥
na ca tasmān manuṣyeṣu kaścin me priya-kṛttamaḥ bhavitā na ca me tasmād anyaḥ priyataro bhuvi