naite guna na gunino mahad-adayo ye
sarve manah prabhrtayah sahadeva-martyah
ady-antavanta urugaya vidanti hi tvam
evam vimrsya sudhiyo viramanti sabdat
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Neither the three modes of material nature [sattva-guna, rajo-guna and tamo-guna], nor the predominating deities controlling these three modes, nor the five gross elements, nor the mind, nor the demigods nor the human beings can understand Your Lordship, for they are all subjected to birth and annihilation. Considering this, the spiritually advanced have taken to devotional service. Such wise men hardly bother with Vedic study. Instead, they engage themselves in practical devotional service.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
As stated in several places, bhaktya mam abhijanati: only by devotional service can the Supreme Lord be understood. The intelligent person, the devotee, does not bother much about the practices mentioned in text 46 (mauna-vrata-sruta-tapo-’dhyayana-sva-dharma). After understanding the Supreme Lord through devotional service, such devotees are no longer interested in studies of the Vedas. Indeed, this is confirmed in the Vedas also. The Vedas say, kim artha vayam adhyesyamahe kim artha vayam vaksyamahe. What is the use of studying so many Vedic literatures? What is the use of explaining them in different ways? Vayam vaksyamahe. No one needs to study any more Vedic literatures, nor does anyone need to describe them by philosophical speculation. Bhagavad-gita (2.52) also says:
yada te moha-kalilam
tada gantasi nirvedam
srotavyasya srutasya ca
When one understands the Supreme Personality of Godhead by executing devotional service, one ceases the practice of studying the Vedic literature. Elsewhere it is said, aradhito yadi haris tapasa tatah kim. If one can understand the Supreme Personality of Godhead and engage in His service, there is no more need of severe austerities, penances and so on. However, if after performing severe austerities and penances one does not understand the Supreme Personality of Godhead, such practices are useless.