hena narayana,--yanra amsera amsa
sei prabhu nityananda--sarva-avatamsa
hena—such; narayana—Lord Narayana; yanra—of whom; amsera—of the plenary part; amsa—apart; sei—that; prabhu—the Lord; nityananda—of the name Nityananda; sarva-avatamsa—the source of all incarnations.
That Lord Narayana is a part of a plenary part of Lord Nityananda Balarama, who is the source of all incarnations.
Link to this page: https://prabhupadabooks.com/cc/adi/5/107