Satapatha Brahmana Part IV (SBE43), Julius Eggeling tr. , at sacred-texts.com
10:5:5:11. Kusri Vâgasravasa 2 once built a fire-altar. Susravas Kaushya then said to him, 'Gautama, when thou wert just now building up Agni, didst thou build him with his face forward, or backward, or downward, or upward?
10:5:5:22. 'If perchance thou hast built him looking forward, it would be just as if one were to offer food from behind to one sitting with averted face 1: he thereby will not receive thy offering.
10:5:5:33. 'And if thou hast built him looking backward, wherefore, then, hast thou made him a tail behind?
10:5:5:44. 'And if thou hast built him with his face downward, it would be just as if one were to put food on the back of one lying with his face downward: he surely will not receive thy offering.
10:5:5:55. 'And if thou hast built him with his face upward--surely, a bird does not fly towards heaven with its face turned upward 2: he will not carry thee to heaven, he will not become conducive to heaven for thee.'
10:5:5:66. He said, 'I have built him with his face forward; I have built him with his face backward; I have built him with his face downward; I have built him with his face upward: I have built him in all directions.'
10:5:5:77. When he lays down the (gold) man with his head forward (eastward), and the two spoons (with their bowls) forward 3, thereby he (Agni) is built looking forward; and when he lays down the
tortoise 1 with its head backward (westward), and the victims’ heads turned backward, thereby he is built looking backward; and when he, lays down the tortoise with its face downward, and the victims’ heads with their faces downward, and the bricks with their faces downward 2, thereby he is built looking downward; and when he lays down the (gold) man with his face upward, and the two spoons (with their open bowls) turned upward, and the mortar turned upward, and the fire-pan turned upward, thereby he is built looking upward; and when he lays down the bricks whilst moving round (the altar) in every direction, thereby he is built (looking) in all directions.
10:5:5:88. Now, the Koshas, whilst driving about, once drove up 3 to an Agni with his head pulled out 4. One of them said, 'The head (siras) means excellence (srî): he has pulled out his excellence, he will be deprived of his all!' and so indeed it happened to him.
10:5:5:99. And another said, 'The head means the vital airs: he has pulled out his vital airs, he will quickly go to yonder world!' and so, indeed, it happened to him.
10:5:5:1010. Upwards, indeed, he (Agni) is built up, to wit, (in the shape of) the grass-bunch, the clod-bricks, the lotus-leaf, the gold plate and man, the two spoons, the naturally-perforated one, the grass-brick, the Dviyagus, the two Retahsik, the Visvagyotis, the two seasonal bricks, the Ashâdhâ, and the tortoise; and that fire which is placed on the altar-pile, assuredly, is then most manifestly his (Agni's) head: let him therefore not pull out (the head).
390:2 That is, Kusri Gautama, (son and) disciple of Vâgasravas.
391:1 The oblations are offered by the Adhvaryu whilst standing south, or south-west, of the fire, with his face turned towards northeast,--hence Agni, looking eastwards, would not see the food offered him.
391:2 Yady agnir uttânas kitas tarhi yathâ uttânam vayah pakshî svayam âkâsam utpatitum na saknoti kim utânyam purusham dvâbhyâm pakshâbhyâm grihîtvotpatitum na sakta iti . . . tvâm kitavantam svargam lokam prâpayitum na saknoty uttâna kayanâd ity arthah; abhivakshyatîti vahah prâpane lriti syapratyaye rûpam. Sây.
391:3 See VII, 4, I, 15. 16.
392:1 See VII, 5, 1, 1.
392:2 Ishtakânâm nîkîtvenopadhânam nâma rigulekhâdakshinâpasavyatryâlikhitâdilekhânâm uparibhâge darsanam. Sây. The broad side of the bricks not marked with lines is thus looked upon as their face.
392:3 That is to say, according to Sâyana, whilst going about officiating at sacrifices, they built the altar in that way at some one's house.
392:4 That is, with a head built on to the altar on the front side of the body; see the diagram of the syenakiti in Burnell's Cat. of Vedic MSS. (1870), p. 29.