CC Ādi 6.82

pitā-mātā-guru-sakhā-bhāva kene naya
kṛṣṇa-premera svabhāve dāsya-bhāva se karaya
Word for word: 
pitā — father; mātā — mother; guru — superior teacher; sakhā — friend; bhāva — the emotion; kene naya — let it be; kṛṣṇa-premera — of love of Kṛṣṇa; svabhāve — in a natural inclination; dāsya bhāva — the emotion of becoming a servant; se — that; karaya — does.
Translation: 
All the emotions, whether those of father, mother, teacher or friend, are full of sentiments of servitude. That is the nature of love of Kṛṣṇa.