Asat is one of the names of God Viṣṇu (Vishnu), as  mentioned in Viṣṇusahasranāmastotra (Vishnusahasranamastotra; The Hymn of Thousand Names of Vishnu).

Mahābhārata (Kinjawadekar)(13.149.64)
Mahābhārata Vols. 1-43 (Siddhāntabāgīśa)(13.127.64)