CC Ādi 6.96

ei saba haya śrī-kṛṣṇera avatāra
nirantara dekhi sabāra bhaktira ācāra
Word for word: 
ei saba — all of them; haya — are; śrī-kṛṣṇera avatāra — incarnations of Lord Kṛṣṇa; nirantara — constantly; dekhi — I see; sabāra — of all; bhaktira ācāra — behavior as devotees.
Translation: 
These are all incarnations of Lord Kṛṣṇa, yet we always find that they act as devotees.