Matsya Purana 58.29

58.29

bahvṛcau pūrvataḥ sthāpyau dakṣiṇena yajurvidau.
sāmagau paścime tadvaduttareṇa tvatharvaṇau.. 58.28 ..

In the east should be seated the Vahavrichas (the two priests versed in the Rigveda), in the south the two Dvârapâlas (learned in the Yajurveda), in the west the two Dvarapâlas (learned in the Sâmveda), and in the north, similarly, the two Dvârapâlas (learned in the Atharva-Veda).—28.