Natyashastra
उपाध्यायस्य नृपतेर्गुरूणामग्रतो बुधैः । भूम्यासनं तथा कार्यमथवा काष्ठमासनम् ॥ २२६॥
The preceptor, the king, the gurus, and the wise elders should be seated in front, either on the ground or on wooden seats.
english translation
upAdhyAyasya nRpatergurUNAmagrato budhaiH । bhUmyAsanaM tathA kAryamathavA kASThamAsanam ॥ 226॥
hk transliteration by Sanscript