Śrīmad-Bhāgavatam 2.10.11
Blended reading (Sanskrit + English inline)
By deriving the name Nārāyaṇa, his dwelling in the water becomes clear. By residing (tena) in that water he got the name Nārāyaṇa because the waters arose from the puruṣa. Nara means the puruṣa. Nāra is that which arises from him. He whose resting place (ayana) is that water (nāra) is called Nārāyaṇa. It is said:
āpo nārā iti proktā āpo vai nara-sūnavaḥ | ayanaṁ tasya tāḥ pūrvaṁ tena nārāyaṇaḥ smṛtaḥ ||
The word āpaḥ and nārā are synonymous for “water” since the waters are considered the sons of Nara, the primeval male or Mahā-viṣṇu. [Note: Nāra means the offspring of Nara. ] Since these waters act as the bed (ayana) of Mahā-viṣṇu from the ancient past, he is called Nārāyaṇa. Viṣṇu Purāṇa 1.4.6
My note
Source: vedabase.io