From Narasimha Purana 17: Vyasa teaches his son Shuka the eight-syllable mantra Om Namo Narayanaya, with its method, colours and fruits.
A litany of 108 names of Lord Vishnu, the Supreme Preserver, chanted on Ekadashi, on Thursdays and in morning prayers with tulasi leaves.
A 43-entry armor from Bhagavata Purana 6.8, taught by Vishvarupa to Indra, placing Vishnu's names, weapons and forms on the body and all directions.
The Purusha Sukta (Rigveda 10.90): the Vedic hymn of the cosmic Purusha, whose sacrifice gives rise to the worlds and the Vedas.