CC Madhya 8.74

prabhu kahe, “eho haya, kichu āge āra”
rāya kahe, “sakhya-prema — sarva-sādhya-sāra”
Synonyms: 
prabhu kahe — the Lord said; eho haya — this is also right; kichu — something; āge — ahead; āra — more; rāya kahe — Rāmānanda Rāya replied; sakhya-prema — transcendental loving service in fraternity; sarva-sādhya-sāra — the highest perfectional stage.
Translation: 
Hearing this from Rāmānanda Rāya, the Lord again requested him to go a step further. In reply, Rāmānanda Rāya said, “Loving service to Kṛṣṇa rendered in fraternity is the highest perfection.
Purport: 

As long as loving service is rendered to the Lord in the master-servant relationship, there is some fear, for the servant is always afraid of the master, despite the intimacy of self-interest. In this stage the servant is always afraid of the master and respectful of Him. When the devotee is further advanced, he has nothing to fear. He considers the Lord and himself on an equal level. At such a time, the devotee is fully convinced that Lord Kṛṣṇa is a friend and cannot at all be dissatisfied if the devotee lives with Him on an equal level. This understanding is called viśrambha, that is, devoid of a respectful attitude. When this attitude is chosen, it becomes sakhya-prema, or love of Godhead in friendship. On this stage there is developed consciousness of equality between the Lord and the devotee.