CC Madhya 20.373

jñāna-śakty-ādi-kalayā
yatrāviṣṭo janārdanaḥ
ta āveśā nigadyante
jīvā eva mahattamāḥ
Word for word: 
jñāna-śakti-ādi-kalayā — by portions of the potencies of knowledge, devotional service, creation, personal service, ruling over the material world, carrying the different planets, and killing the rogues and miscreants; yatra — wherever; āviṣṭaḥ — is entered; janārdanaḥ — the Supreme Personality of Godhead, Viṣṇu; te — they; āveśāḥ — empowered; nigadyante — are called; jīvāḥ — living entities; eva — although; mahat-tamāḥ — most exalted devotees.
Translation: 
“ ‘Whenever the Lord is present in someone by portions of His various potencies, the living entity representing the Lord is called a śaktyāveśa-avatāra — that is, an incarnation invested with special power.’
Purport: 

This verse is found in the Laghu-bhāgavatāmṛta (1.18).