Śatapatha Brāhmaṇa ("of a hundred paths") 1.3.3.5

1.3.3.5

atha visraṃsya granthim | purastātprastaraṃ gṛhṇāti viṣṇo stupo 'sīti yajño vai viṣṇustasyeyameva śikhā stupa etāmevāsminnetaddadhāti purastādgṛhṇāti purastāddhyayaṃ stupastasmātpurastādgṛhṇāti

Having thereupon untied the knot, he takes the prastara bunch from the front (of the barhis), with the text (Vâg. S. II, 2), 'Vishnu's crest art thou!' Vishnu, namely, is the sacrifice, and this (the prastara) is his top-knot or crest: this he thereby makes it at this sacrifice. From the front he takes it, because this top-knot also is (worn) on the front (of the head): for this reason he takes it from the front.