BG 11.52-54
The Blessed Lord said: This Form of Mine beholden by thee is very hard to see. Verily the Shining Ones ever long to behold this form. Nor can I be seen as thou hast seen Me by the Vedas, nor by austerities, nor by alms, or by offerings; But by devotion to Me alone I may thus be perceived, Arjuna, and known and seen in essence, and entered, O Parantapa.