Bhagavad Gita Chapter 11, Text 53

Bg 11.53

naham vedair na tapasa
na danena na cejyaya
sakya evam-vidho drastum
drstavan asi mam yatha

Word for word: 
na — never; aham — I; vedaih — by study of the Vedas; na — never; tapasa — by serious penances; na — never; danena — by charity; na — never; ca — also; ijyaya — by worship; sakyah — it is possible; evam-vidhah — like this; drastum — to see; drstavan — seeing; asi — you are; mam — Me; yatha — as.

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The form you are seeing with your transcendental eyes cannot be understood simply by studying the Vedas, nor by undergoing serious penances, nor by charity, nor by worship. It is not by these means that one can see Me as I am.

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Krishna first appeared before His parents Devaki and Vasudeva in a four-handed form, and then He transformed Himself into the two-handed form. This mystery is very difficult to understand for those who are atheists or who are devoid of devotional service. For scholars who have simply studied Vedic literature by way of grammatical knowledge or mere academic qualifications, Krishna is not possible to understand. Nor is He to be understood by persons who officially go to the temple to offer worship. They make their visit, but they cannot understand Krishna as He is. Krishna can be understood only through the path of devotional service, as explained by Krishna Himself in the next verse.