The term anagha has been used twice to refer to Viṣṇu (Vishnu) in the stotra of his one thousand names (Viṣṇu Sahasranāmastotra; Vishnu Sahasranamastotra). The word agha means vice, unhappiness or sin. In Upaniṣadas (Upashinadas) the absolute brahma or the Supreme Being is imagined as a formless embodiment who is beyond earthly qualities such as virtue or vice.
In this sense, he has been called apahatapāpmā, meaning viceless or sinless. God Viṣṇu is the true form of the Absolute One, and hence he is also above corporeal or human demerits such as crime or sin. Thus, he is known as Anagha.
Aghaṃ na vidyate’syeti anaghaḥ.
Or, aghaṃ duḥkhaṃ pāpaṃ casya na vidyata iti anaghaḥ. [Śāṅkarabhāṣya; Annotations by Śaṅkarācārya (Shankaracharya)].