Śatapatha Brāhmaṇa ("of a hundred paths") 3.7.1.3

3.7.1.3

atha khanati | prāñcamutkaramutkiratyupareṇa sammāyāvaṭaṃ khanati tadagreṇa prāñcaṃ yūpaṃ nidadhātyetāvanmātrāṇi barhīṃṣyupariṣṭādadhinidadhāti tadevopariṣṭādyūpaśakalamadhinidadhāti purastātpārśvataścaṣālamupanidadhātyatha yavamatyaḥ prokṣaṇyo bhavanti so 'sāveva bandhuḥ

He then digs, and throws up a heap of earth towards the east. He digs the hole, making it equal (in depth) with the (unhewn) bottom part (of the stake). In front of it he lays down the stake with the top towards the east. Thereon he puts sacrificial grass of the same size, and thereupon he puts the chip of the stake. In front on the (north) side (of the stake) he puts down the head-piece. The sprinkling-water has barley-corns mixed with it: the significance of this is the same (as before).