CC Ādi 5.137

āpanāke bhṛtya kari’ kṛṣṇe prabhu jāne
kṛṣṇera kalāra kalā āpanāke māne
Word for word: 
āpanāke — Himself; bhṛtya kari’ — considering a servant; kṛṣṇa — Kṛṣṇa; prabhu — master; jāne — He knows; kṛṣṇera — of Lord Kṛṣṇa; kalāra kalā — as a plenary portion of a plenary portion; āpanāke — Himself; māne — He accepts.
Translation: 
He considers Himself a servant and knows Kṛṣṇa to be His master. Thus He regards Himself as a fragment of His plenary portion.