Vishnupurana 2.8.p9

2.8.p9

The night is called Ushā and the day is called Vyushta and the intervening time between them is called Sandhyā. When the dreadful Sandhya sets in, the awful Rākshasas named Mandehas attempt to devour the sun. O Maitreya, the Patriarch Brahmā imprecated this curse upon them that they should perish by day and revive at other times. For this reason a fierce contest takes place daily between them and the sun. At this time, O great Muni, the pious Brahmins scatter water purified by the mystical Omkāra and consecrated by the Gayatri and by means of this water as by a thunder-bolt the dreadful Rākshasas are destroyed. While during the course of morning rites the first oblation is offered with solemn invocations, the sun, having thousand rays, appears with unclouded splendour. Omkāra is the glorious Vishnu, the essence of the three Vedas, the lord of speech; and by its mention the Rākshasas are slain. The sun is a principal portion of Vishnu and light is his immutable essence, the manifestation of which is made by the mystic syllable Om. Light, spread by the utterance of Omkāra, becomes radiant and burns up completely the Rākshasas denominated as Mandebas. Therefore one should not be dilatory in the performance of Sandhyā sacrifice; for he, who neglects it, is guilty of the murder of the sun. Being thus protected by the Brahmanas called Bālakhilyas the sun proceeds to protect the world.