Kauthumagrihyasutra 9

Now, in the fourth month, the parting of the hair (sīmantonnayana) should be performed. The ancestral offering for prosperity (nāndīmukha) [is performed] on the preceding day. Then, having bathed at dawn on the following day, the patron of the sacrifice, following the sequence of the rite for producing a male child (puṃsavana), brings an udumbara branch to the house. And having cooked rice grains mixed with sesame with a porcupine quill that has three white rings on the common fire, and having placed it to the north of the sacrificial ground, having performed [the ritual] up to the introductory formula (prapada) as before, having made the offering of the kindling sticks (idhmāṅga), and having offered again with the three mystic utterances (vyāhṛti); then the patron of the sacrifice, standing behind, taking that udumbara branch, or having muttered 'ayam ūrjā...', looking at the tip of the nose, parts [her hair upwards]... having said 'yenāditih...'; taking [it] again with the quill, according to some [with the verse to] Rākā; establishing [it], having silently performed consecration by sprinkling three times, sitting in his own place, then having completed the subsequent offerings, having made the wife who holds the vessel say, 'What do you see?', having sung the Vāmadevya chant, then the feeding of brahmins, then the feeding of brahmins.

KauthGS 10: