SB 11.20.35

nairapekṣyaṁ paraṁ prāhur
 niḥśreyasam analpakam
tasmān nirāśiṣo bhaktir
 nirapekṣasya me bhavet
Synonyms: 
nairapekṣyam — not desiring anything except devotional service; param — the best; prāhuḥ — it is said; niḥśreyasam — highest stage of liberation; analpakam — great; tasmāt — therefore; nirāśiṣaḥ — of one who does not seek personal rewards; bhaktiḥ — loving devotional service; nirapekṣasya — of one who only sees Me; me — unto Me; bhavet — may arise.
Translation: 
It is said that complete detachment is the highest stage of freedom. Therefore, one who has no personal desire and does not pursue personal rewards can achieve loving devotional service unto Me.
Purport: 

As stated in Śrīmad-Bhāgavatam (2.3.10):

akāmaḥ sarva-kāmo vā
 mokṣa-kāma udāra-dhīḥ
tīvreṇa bhakti-yogena
 yajeta puruṣaṁ param

“A person who has broader intelligence, whether he be full of all material desire, without any material desire or desiring liberation, must by all means worship the supreme whole, the Personality of Godhead.” In this statement by Śukadeva Gosvāmī, the words tīvreṇa bhakti-yogena are very significant. Śrīla Prabhupāda remarks in this regard, “As the unmixed sun ray is very forceful and is therefore called tīvra, similarly, unmixed bhakti-yoga of hearing, chanting, etc., may be performed by one and all regardless of inner motive.” Undoubtedly, in this Age of Kali people are generally very fallen and polluted by material lust, greed, anger, lamentation and so forth. In this age most people are sarva-kāma, or full of material desires. Still we must understand that simply by taking shelter of Lord Kṛṣṇa we will achieve everything in life. The living entity should not engage in any process except the loving service of the Lord. One must accept that Lord Kṛṣṇa is the reservoir of all pleasure and that only Lord Kṛṣṇa within our heart can fulfill our real desire. This simple faith that one will achieve everything by approaching Lord Kṛṣṇa is the essence of all knowledge and carries even a fallen person over the painful hurdles of this difficult age.