CC Ādi 4.27-28

ei śuddha-bhakta lañā karimu avatāra
kariba vividha-vidha adbhuta vihāra
vaikuṇṭhādye nāhi ye ye līlāra pracāra
se se līlā kariba, yāte mora camatkāra
Word for word: 
ei — these; śuddha-bhakta — pure devotees; lañā — taking; karimu — I shall make; avatāra — incarnation; kariba — I shall do; vividha-vidha — various kinds; adbhuta — wonderful; vihāra — pastimes; vaikuṇṭha-ādye — in the Vaikuṇṭha planets, etc; nāhi — not; ye ye — whatever; līlāra — of the pastimes; pracāra — broadcasting; se se — those; līlā — pastimes; kariba — I shall perform; yāte — in which; mora — My; camatkāra — wonder.
Translation: 
“Taking these pure devotees with Me, I shall descend and sport in various wonderful ways, unknown even in Vaikuṇṭha. I shall broadcast such pastimes by which even I am amazed.
Purport: 

Lord Kṛṣṇa in the form of Lord Caitanya educates His devotees to develop progressively to the stage of pure devotional service. Thus He appears periodically as a devotee to take part in various wonderful activities depicted in His sublime philosophy and teachings.

There are innumerable Vaikuṇṭha planets in the spiritual sky, and in all of them the Lord accepts the service rendered by His eternal devotees in a reverential mood. Therefore Lord Śrī Kṛṣṇa presents His most confidential pastimes as He enjoys them in His transcendental realm. Such pastimes are so attractive that they attract even the Lord, and thus He relishes them in the form of Lord Caitanya.