The works of Ādi Śaṅkarācārya

Viṣṇusahasranāmastotram

Verse 243

इति विष्णुपुराणे ।

In plain words

So it stands in the Viṣṇu Purāṇa.

Close to the Sanskrit

Thus, in the Viṣṇu Purāṇa.