If one has material desires or motives within himself, and for fulfillment of such desires he engages himself in devotional service, the result will be that he will never get pure love of God. If one is thinking, “I am engaged in Kṛṣṇa consciousness, in Kṛṣṇa’s devotional service, because I want such and such an opulence,” that desire may be fulfilled, but he will never get such unalloyed love of Kṛṣṇa as the gopis had. If one has a motive, even though he discharges his devotional duty, he still will not be able to reach the stage of pure love of Godhead. In other words, if one has material desires, or even a desire for salvation, he cannot attain pure love of Godhead. Pure devotion is devoid of all desires-it is simply to render loving service for its own sake.
There is no ambition or motive in pure Kṛṣṇa consciousness. Every other transcendental function or mode of worship is backed by a motive: someone wants salvation, someone wants material prosperity, someone wants to go to a higher planet, and someone wants to go to Kṛṣṇaloka. These ambitions should not be there. A pure devotee has no such ambitions. A pure devotee does not even desire to go to the supreme abode of Kṛṣṇa. Of course, he goes, but he has no desire. He simply wants to engage himself fully in Kṛṣṇa’s service. The highest perfection of devotional service, or Kṛṣṇa consciousness, is exhibited when a devotee refuses to accept any benediction or profit from the Supreme Lord. Prahlada Maharaja was offered whatever he liked, he had only to ask for it, but he said, “My Lord, I am Your eternal servant. It is my duty to serve You, so how can I accept any benefit from it? Then I would not be Your servant; I would be a merchant.” He replied in that way, and that is the sign of a pure person.
Srila Bhaktisiddhanta Sarasvati Thakura used to say that asking God for mukti or anything else other than bhakti is like going to a rich man and asking for ashes. There is another story, about an old woman who was carrying a bundle of dry wood through the forest. Somehow or other the bundle, which was very heavy, fell to the ground. The old woman became very disturbed, and thought, “Who will help put this bundle back on my head?” She then began to call on God, saying, “God help me.” Suddenly God appeared and said, “What do you want?” She said, “Please help me put this bundle back on my head.” So this is our foolishness. When God comes to give us some benediction, we simply ask Him to load us down again with all these material bundles. We ask Him for more material things, for a happy family, for a large amount of money, for a new car or whatever.
Kṛṣṇa is so kind that He fulfills all the desires of a devotee, even if he wants material benedictions. If at the bottom of the devotee’s heart there is some desire, He also fulfills that. He is so kind. But the sublime position of bhakti-yoga, or devotional service, is that a pure devotee refuses to accept the various kinds of liberation, even if offered by the Supreme Lord.
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “The Science of Self-Realization”, Page 340
A.C. Bhaktivedanta Swami Prabhupada (2007 edition), “Teachings of Lord Kapila, The Son of Devahuti”, Page 196