Kauṣītaki (Śāṅkhāyana) Brāhmaṇa 2.p13

2.p13

he offers with ‘Hail!’ This offering of him of true offering the gods accept. At the head of night he speaks truth; if indeed even henceforth he speaks falsely, still truth is uttered by him, for at the head of night he speaks truth. He offers in the morning (saying) ‘The light is the sun, the sun is the light.’ Him that is light he calls light; he speaks the truth; his self here, being composed of speech, becomes composed of truth; the gods also are composed of truth. Again, he offers with ‘Hail!’ This offering of him of true offering the gods accept. At the head of day he speaks truth; if indeed even henceforth he speaks falsely, still truth is uttered by him, for at the head of day he speaks truth. The fire here offers itself in the rising sun; yonder sun, when setting, offers itself in the fire at evening; the night also (offers itself) in day, the day in night; the expiration also offers in inspiration, the inspiration in expiration. These six sacrifice themselves, each in the other; he who knows these six in the sacrificer, by him even if he sacrifices not is offering made; and if he does sacrifice twice is offering made by him who knows thus. If indeed even from a very small portion, knowing thus, he offers the Agnihotra, these two offerings of his the gods accept, and he whose (offerings) the gods once eat, from that time he is immortal. Composed of truth and immortality does he become who knows thus. Just as is the offering of a man who has faith as his deity, who speaks the truth, and is full of fervour, such is the offering of him who, knowing thus, offers the Agnihotra. Therefore (they say) one knowing thus should offer the Agnihotra.