Viṣṇu is the Brahmanical god who preserves the universe, frequently as an avatāra, or descent. The Buddha is incorporated into Viṣṇu's mythology, most clearly in the Gayā-mahatmya (Praises of the Greatness of Gaya) section of the Vāyu-purāṇa (Ancient Book of Vāyu), in which Viṣṇu assumes the form of the Buddha and preaches false teachings to a group of asuras. Viṣṇu himself is not a particularly important textual presence, but in Sri Lanka he is frequently worshiped by Buddhists, often as one of the protectors of the religion and as a powerful, active force.
Gonda, Jan. Aspects of Early Viṣṇuism. Delhi: Motilal Banarsidass, 1965.
The Vāyu Purana, tr. G. V. Tagare. Delhi: Motilal Banarsidass, 1987.
Jacob N. Kinnard