Shatapatha Brahmana 7.1.1.31

7.1.1.31

bāhū asyaite | te nānopadadhāti nānā sādayati nānā sūdadohasādhivadati nānā hīmau bāhū dve bhavato dvau hīmau bāhū pūrvārdha upadadhāti purastāddhīmau bāhū agrābhyāṃ saṃspṛṣṭe bhavata evaṃ hīmau bāhū agrābhyāṃ saṃspṛṣṭau sa vā itīmā upadadhātītīme itīme taddakṣiṇāvṛttaddhi devatrā

These two are his (Agni's) arms,--separately he puts them on, separately he 'settles' them, separately he pronounces the Sûdadohas verse on them; for separate are these two arms. There are two of them, for there are two arms. He puts them on in the forepart, for these arms are here in front. At their upper ends they are joined (to the central ones), for so are these two arms joined (to the body) at the upper ends. Those two (arms) he puts on thus (from north to south), and those two (thighs) thus (from south to north): that is (from east to) southward, for thus it is with the gods.