Manava Dharmashastra 2.110

2.110

adhīyānenānupasannena yadi nāśitamapākṣaraṃ visvaraṃ vā'dhītaṃ tadā'pṛṣṭena na vaktavyam 'nāśitaṃ tvayaivametatpaṭhitavyamiti' | śiṣyasya tvapṛcchato'pi vaktavyam | pṛcchamāno'pi yadyanyāyena pṛcchati tathāpi na vaktavyam | praśrayapūrvakam, 'asminvastuni me sandehastadupadeṣṭumarhasīti' śiṣyadharmeṇa praśno nyāyena | anyathā tu jānannapi jaḍavat mūka iva loke varteta ācaredajña iva tūṣṇīmāsīta | śāstraviṣayo'yamapṛṣṭasandehāpanayananiṣedhaḥ | vyavahāre tu vakṣyati "niyukto vā'niyukto vā dharmajño vaktumarhatīti|" anye tvaviśeṣeṇecchanti |

One should not instruct any one unless he is asked; nor any one who asks in an improper manner. even though knowing (the truth), the wise man should behave, among men, as if ignorant.—(110)

Medhātithi’s commentary (manubhāṣya):
If a person, who is not his regular pupil, but is reading near him, should murder the text, or omit certain letters, or read with a wrong accent,—the learned man should not, unless he is asked to (correct), instruct the student and tell him ‘you have murdered the text, you should read it thus.’ If the reader happen to he his own pupil, then he should instruct him, even without being asked. If again the student were to ask, but ask in an improper manner,—then also he should not instruct him. The ‘proper manner’ of asking is to ask with due humility, in the manner of a pupil, with such words as—‘in this matter I have a doubt, pray instruct me on this point.’ In cases other than this, ‘even though knowing the truth, the wise man should behave’—continue to live—among men, ‘as if ignorant,’—as if he were dumb; i.e., he should remain silent, as if he did not know anything.

This prohibition regarding the explaining of doubts without being asked refers to scriptural matters; as regards temporal matters, the author is going to declare that—‘Employed or not employed (by the king) the man knowing the law should expound it.’ Others have held that the prohibition contained in the present verse applies equally to both scriptural and temporal matters.—(110)