Manusmriti
प्रतिवातेऽनुवाते च नासीत गुरुणा सह । असंश्रवे चैव गुरोर्न किं चिदपि कीर्तयेत् ॥ २०३ ॥
Let him not sit with his teacher, to the leeward or to the windward (of him); nor let him say anything which his teacher cannot hear.
english translation
prativAte'nuvAte ca nAsIta guruNA saha । asaMzrave caiva gurorna kiM cidapi kIrtayet ॥ 203 ॥
hk transliteration by Sanscript