Śatapatha Brāhmaṇa ("of a hundred paths") 3.2.1.13

3.2.1.13

muñjavalśenānvastā bhavati | vajro vai śaro virakṣastāyai stukāsargaṃ sṛṣṭā bhavati sā yatprasalavi sṛṣṭā syādyathedamanyā rajjavo mānuṣī syādyadvapasalavi sṛṣṭā syātpitṛdevatyā syāttasmātstukāsargaṃ sṛṣṭā bhavati

It is intertwined with a shoot of reed (muñga) grass, for the sake of chasing away the evil spirits, the reed being a thunderbolt. It is plaited after the manner of a braid of hair. For were it to be twisted sunwise (from left to right) as any other cords, it would be human; and were it twisted contrary to the course of the sun, it would be sacred to the Fathers: hence it is plaited after the manner of a braid of hair.