Jaiminīya (Talavakāra) Brāhmaṇa 2-3.20

2-3.20

for, lacking ritual form, they become like mere lumps. One should chant limb by limb. They indeed come into being in that world endowed with limbs, endowed with bodies, immortal. Now some make the sound hiṃ only once for the head, saying: "The head is facing away from this [chant]." Three times each for the other limbs. Those make thirteen hiṃ-sounds. "Thus is the attainment of the thirteenth month." But that is certainly not so. Making the sound hiṃ three times for the head, three times each for the other limbs, those make fifteen hiṃ-sounds. Indra is fifteen-fold; the Mahāvrata belongs to Indra: that is made possessed of its characteristic sign.