Varahashrautasutra 2.2.3.13

2.2.3.13

āgneyapāvamānyāṃ gāyatraṃ gāyati śirasi rathantaraṃ dakṣiṇasminpakṣe | bṛhaduttarasmin | vāmadevyaṃ dakṣiṇasyām̐ śroṇyām | pucche yajñāyajñiyam | prajāpaterhṛdayamanṛcamapipakṣe

On an Āgneyī-pāvamānī [verse], he sings the Gāyatra sāman; at the head, the Rathantara; on the right wing, the Bṛhat; on the left wing, the Vāmadevya; on the right hip; on the tail, the Yajñāyajñīya; Prajāpati's heart [is sung] without a verse on the wing.