YV 5.1j

Then he burns at the end the plants; they then grow more numerous. In that he offers in the evening, he thus pours seed, and makes it productive by the morning (offering). Seed when poured does not prove fruitful unless modified by Tvastr; as many modifications of seed when poured [1] as Tvastr makes, in so many shapes does it become fruitful; the sacrificer is the divine Tvastr. He pays reverence with many (verses); verily he makes many modifications of the seed when poured. He is fruitful and day by day becomes greater, who knowing thus pays reverence to the fire. The day was the gods', the night the Asuras'. The Asuras entered night with all the precious wealth of the gods [2]; the gods thought that they were abandoned; they perceived, 'The night is Agni's, cattle are Agni's; verily let us praise Agni here; he being praised by us will restore our cattle.' They praised Agni; be praised by them delivered their cattle from night to day; the gods having gained their cattle per formed their desires. He who knowing thus pays reverence to the fire becomes possessed of cattle [3]. The sun went from this world to yonder world; he having gone to yonder world bethought him again of this world; having returned to this world he had fear of death, for this world is, as it were, yoked with death. He reflected, 'Let me praise Agni here; he, praised, will make me go to the world of heaven.' He praised Agni; he, praised, made him go to the world of heaven. He who [4] knowing thus pays reverence to the fire, goes to the world of heaven and lives all his days. He mounts these two fires who pays reverence to them; he acts according to the desires of one who has attained a higher place. He pays reverence at night, not in the morning, for vows are mingled at night, the bad and the good are on the same level, the fire is the light, the evening is the darkness; in that [5] he pays reverence by night, he overcomes the darkness by light. 'Should reverence be paid to the fire or not?