Śatapatha Brāhmaṇa ("of a hundred paths") 3.3.2.4

3.3.2.4

yadyuṣṇīṣaṃ vindet | uṣṇīṣaḥ syādyadyuṣṇīṣaṃ na vindetsomaparyāṇahanasyaiva dvyaṅgulaṃ vā tryaṅgulaṃ vāvakṛnteduṣṇīṣabhājanamadhvaryurvā yajamāno vā somopanahamādatte ya eva kaśca somaparyāṇahanam

If he can get a head-band, let there be a headband; but if he cannot get a head-band, let him cut off from the Soma-wrapper a piece two or three fingers long, to serve as the head-band. Either the Adhvaryu or the Sacrificer takes the Soma-cloth, and some one or other the Soma-wrapper.