The Vishnu Sahasranama is the thousand names of Vishnu, arranged in about a hundred and eight verses within the Mahabharata, where the dying patriarch Bhishma imparts them to Yudhishthira. It is recited in full daily by many Vaishnava households, a recitation of roughly half an hour, and it is a hymn made almost entirely of epithets: each name is a compressed statement about the deity, the pervader, the imperishable, the beginningless, the support of all, the one of a thousand forms, so that to recite the whole is to run through a catalogue of the divine attributes.
The form has a theology built into it. By naming Vishnu a thousand ways the hymn insists that no single name or aspect exhausts him, and the sheer accumulation becomes an act of devotion in which the reciter contemplates the god from a thousand angles in turn. Shankara, the great Advaita philosopher, wrote a commentary on it, and its names have been read and re-read across the Vaishnava schools, each finding its own emphases. The genre of the thousand-names hymn (sahasranama) exists for many deities, but Vishnu's is the most celebrated, and it is a characteristic Hindu solution to the problem of praising the infinite: not one perfect name, but a thousand.