Srimad Bhagavatam Canto 04, Chapter 24, Text 54

SB 4.24.54

bhavan bhaktimata labhyo
 durlabhah sarva-dehinam
svarajyasyapy abhimata
 ekantenatma-vid-gatih
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
My dear Lord, the king in charge of the heavenly kingdom is also desirous of obtaining the ultimate goal of life — devotional service. Similarly, You are the ultimate destination of those who identify themselves with You [aham brahmasmi]. However, it is very difficult for them to attain You, whereas a devotee can very easily attain Your Lordship.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
As stated in Brahma-samhita, vedesu durlabham adurlabham atma-bhaktau. This indicates that it is very difficult for one to attain the ultimate goal of life and reach the supreme destination, Vaikunthaloka or Goloka Vrndavana, simply by studying Vedanta philosophy or Vedic literature. However, this highest perfectional stage can be attained by the devotees very easily. That is the meaning of vedesu durlabham adurlabham atma-bhaktau. The same point is confirmed by Lord Siva in this verse. The Lord is very difficult for the karma-yogis, jñana-yogis and dhyana-yogis to attain. Those who are bhakti-yogis, however, have no difficulty at all. In the word svarajyasya, svar refers to Svargaloka, the heavenly planet, and svarajya refers to the ruler of the heavenly planet, Indra. Generally, karmis desire elevation to heavenly planets, but King Indra desires to become perfect in bhakti-yoga. Those who identify themselves as aham brahmasmi (“I am the Supreme Brahman, one with the Absolute Truth”) also ultimately desire to attain perfect liberation in the Vaikuntha planets or Goloka Vrndavana. In Bhagavad-gita (18.55) it is said:
 
bhaktya mam abhijanati
 yavan yas casmi tattvatah
tato mam tattvato jñatva
 visate tadanantaram
 
“One can understand the Supreme Personality as He is only by devotional service. And when one is in full consciousness of the Supreme Lord by such devotion, he can enter into the kingdom of God.”
 
Thus if one desires to enter into the spiritual world, he must try to understand the Supreme Personality of Godhead by practicing bhakti-yoga. Simply by practicing bhakti-yoga one can understand the Supreme Lord in truth, but without such understanding, one cannot enter the spiritual kingdom. One may be elevated to the heavenly planets or may realize himself as Brahman (aham brahmasmi), but that is not the end of realization. One must realize the position of the Supreme Personality of Godhead by bhakti-yoga; then real perfection of life is attained.
Srimad Bhagavatam Canto 04, Chapter 24, Text 53
Srimad Bhagavatam Canto 04, Chapter 24, Text 55