The sixth incarnation of the puruṣa was the son of the sage Atri. He was born from the womb of Anasūyā, who prayed for an incarnation. He spoke on the subject of transcendence to Alarka, Prahlāda and others [Yadu, Haihaya, etc.].
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
षष्ठमत्रेरपत्यत्वं वृतः प्राप्तोऽनसूयया । (षष्ठे अत्रे) आन्वीक्षिकीमलर्काय प्रह्लादादिभ्य ऊचिवान्
ṣaṣṭhamatrerapatyatvaṃ vṛtaḥ prāpto'nasūyayā | (ṣaṣṭhe atre) ānvīkṣikīmalarkāya prahlādādibhya ūcivān
SB 1.3.11