Nārāyaṇāya is the third and longest component of the Aṣṭākṣara (Oṃ Namo Nārāyaṇāya), comprising five syllables: na-rā-ya-ṇā-ya. Grammatically it is the dative singular of Nārāyaṇa, expressing 'unto Nārāyaṇa' or 'for the sake of Nārāyaṇa.' In Śrī Vaiṣṇava pāribhāṣika interpretation, this case-ending declares the purpose of the ātmā's existence — the jīva belongs to Nārāyaṇa and exists solely for His pleasure (śeṣatva).
The ācāryas teach that Nārāyaṇāya encodes three profound truths: (1) Bhagavān is the ultimate goal (prāpya); (2) all kaiṅkarya — service rendered freely by the liberated soul — is offered to Him alone; and (3) the fourth case (caturthi vibhakti) indicates that the ātmā's happiness is complete only in serving Him. Piḷḷai Lokācārya explains in Mumukṣuppati that this word signals that the self must not serve anyone else (anyaśeṣatva-niṣedha) and must not even enjoy itself as its own end (svārtha-niṣedha).
In the context of prapatti, Nārāyaṇāya seals the surrender: just as namaḥ renounces self-effort, this dative dedicates the prapanna irrevocably to Bhagavān. Maṇavāḷa Māmunigaḷ notes that meditating on this word at the moment of prapatti dissolves the jīva's misconceived independence and replaces it with the bliss of pāratantrya, absolute dependence on the Lord.