The Religion and Philosophy of the Veda and Upanishads v2.c30.s3.4

v2.c30.s3.4

There can be little doubt that even as early as the Rigveda there was present the idea that the Agnihotra, with its brightening up of the fires, was a spell to aid the rising of the sun, a view which was doubtless the ground of the opinion of those who pressed for the performance of the ceremony before sunrise.³