Caitanya-caritāmṛta 5.107
hena nārāyaṇa, — yāṅra aṁśera aṁśa sei prabhu nityānanda — sarva-avataṁsa
[hena naaraayana, — yaanra amshera amsha sei prabhu nityaananda — sarva-avatamsa]
Blended reading (Sanskrit + English inline)
hena nārāyaṇa, — yāṅra aṁśera aṁśa sei prabhu nityānanda — sarva-avataṁsa
That Lord Nārāyaṇa is a part of a plenary part of Lord Nityānanda Balarāma, who is the source of all incarnations.
My note
Source: vedabase.io