Manava Dharmashastra 4.236

4.236

tapasā'nuṣṭhitena vismayaṃ na kuryāt | atitīvraṃ tapo mayā kṛtaṃ suduśvaramityevaṃ manasi na kartavyam | iṣṭvā yāgaṃ kṛtvā'nṛtaṃ na vadet | aviśeṣeṇa pratiṣiddhasyāpi puruṣārthatayā punaḥ pratiṣedho yāgāṅgatvajñāpanārthaḥ | pratiṣedhātikrame hi jyotiṣṭomāderaṅgahīnatā bhavati | ārttaḥ pīḍito'pi brāhmaṇairna tānapavadena nindeta | datvā gavādi dravyaṃ na kasyacidagrataḥ parikīrtayedidaṃ mayā dattam |

Medhātithi’s commentary (manubhāṣya):
When he performs an austerity, he shall not boast of it,—‘I have performed a most severe austerity, extremely difficult to perform;’ he shall not entertain any such idea.

‘Having performed a sacrifice, he shall not utter a lie.’—Though lying in general has been forbidden, in connection with what is desirable for men, yet it is forbidden again, with a view to indicate that the avoidance of untruth is an essential factor in sacrifices also; and that, if there is a transgression of this, the performance of the Jyotiṣṭoma, etc., would become defective.

‘Tormented’— by the Brāhmaṇas—‘he shall not revile’—abuse, speak ill of—them.

‘Having bestowed a gift’— in the form of the cow and such other things,—‘he shall not advertise it’ before another person, saying, ‘Such and such a gift has been bestowed by me.’—(236)