Manava Dharmashastra 2.203

2.203

yasyāṃ diśi gururvyavasthitastato deśādyadā vāyuḥ śiṣyadeśamāgacchati śiṣyadeśācca gurudeśaṃ te prativātānuvāte | ekaṃ ‘prativātam’ aparam ‘anuvātam’ tadapekṣayā guruṇā saha nāsīta —api tu tiryagvātasevī gurorbhavet |
avidyamānaḥ saṃśravo yatra tasmin asaṃśrave | na kiñcidapi gurugatamanyagataṃ vā kīrtayet | yatra gururvyaktaṃ na śṛṇoti, oṣṭhasañcalanādinā śiṣyasambandhinā jānāti kiñcidayametena sambhāṣate, tanna kīrtayet |

Medhātithi’s commentary (manubhāṣya):
When the wind comes from the side on which the Teacher is sitting to where the pupil sits,—and when it comes from where the pupil sits to when the Teacher is,—these are called ‘lee-ward’ and ‘wind-ward’; one being ‘lee-ward’ and the other ‘wind-ward.’ In either of these fashions one should not sit in the Teacher’s company; be should sit in such a fashion that he gets the wind sideways.

‘Beyond his hearing’;—i.e., wbat he cannot hear.

‘Nothing,’—with reference either to the Teacher or to other persons.

‘He should say’—nothing, what the Teacher cannot hear, but can see from the moving of the lips that the pupil is saying something.—(203)