Śatapatha Brāhmaṇa ("of a hundred paths") 9.2.3.47

9.2.3.47

athātaḥ sampadeva | ṣaṭ purastājjuhoti ṣaḍupariṣṭātṣadbhirāśmanaḥ pṛśneryanti dvābhyāmaśmānam pṛśnimupadadhāti caturbhirāgneryanti pañcabhiragnimārohanti tadekāṃ na triṃśadāhutireva triṃśattamī dvābhyāmagnim nidadhāti taddvātriṃśaddvātriṃśadakṣarānuṣṭupsaiṣānuṣṭup

Now, then, as to the (mystic) correspondence (or, amount). Six he offers before (the leading forward of the fire), and six afterwards; with six (formulas) they proceed up to the variegated stone; with two he lays down the variegated stone; with four they proceed as far as the fire-altar; with five they mount the fire-altar: that makes twenty-nine, and the oblation itself is the thirtieth. With two (verses) he deposits the fire,--that makes thirty-two, and of thirty-two syllables consists the Anushtubh: such, then, is this Anushtubh.