Paraskaragrihyasutra 2.10.18

2.10.18

prāśanānte pratyaṅmukhebhya upaviṣṭebhya ?kāramuktvā triśca sāvitrīmadhyāyādīnprabrūyāt \18\

After they have eaten (the remainder of the sacrificial food, the teacher) should pronounce the word Om and then repeat the Sâvitrî three times, and the beginnings of the Adhyâyas to (the students) who are seated facing the west;