Brahma Purana says that the twelve Adityas reckoned separately are Visnu, Daksa, Bhaga, Pusan, Mitra, Indra, Aruna, Aryama, Vivasvan, Arusuman, Tvastr and Parjanya. They are separate forms of the sun-god rising in twelve months respectively. It is said that Vishnu blazes in the month of Chaitra, Aryama in Vaisakha; Vivasvan in Jyestha and Arusuman in Asadha. Parjanya blazes in the month of Shravana, Varuna in Prausthapada, Indra in Asvayuja and Dhatr in Kartika. Mitra blazes in the month of Margasirasa and Pusa, Bhaga in Magha and Tvastr in the month of Phalguna.
It is believed that an individual should recite the names of sun-god in prayer with utter dedication in order to achieve merit and goodness in life. Apart from the twelve general names of the sun-god there are twenty one other names of the lord which is uttered during prayer to the lord. The twenty one names of the lord are Vikartana, Vivasvan, Martanda, Bhaskara, Ravi, Lokaprakasaka, Srlman, Lokacaksus, Mahesvara, Lokasaksi, Trilokesa Karta, Harta, Tamisraha, Tapana, Tapana, Suchi, Saptasvavahana, Gabhastihasta, Brahmanya and Sarvadevanamaskrta.
According to Brahma Purana the prayer consisting of all the names of the lord is a royal prayer. It is well known in the three worlds. It is conducive to the health of body. Such prayer increases the riches and enhances glory. He who remains pure and eulogises the Sun-god with this hymn at the two junctions that is sunrise and sunset, is liberated from all sins. The belief goes that by repeating this hymn at least once in the presence of the sun-god all sins perish whether they are mental, physical or verbal or caused by other activities. It is said that when this hymn is repeated it becomes the Mantra of Homa and when the hymn having the names of sun-god are repeated in the twilight it becomes the mantra for incense, for Arghya and for oblations too.
It has been mentioned in the Purana that an individual should utter the hymn having the names of the god because it is the sun-god who is the bestower of all goods and also grants all cherished desires to individuals.