BṚHADĀRAṆYAKA UPANISHAD · 1.3.2

ते ह वाचम् ऊचुस् त्वं न उद्गायेति ।
तथेति तेभ्यो वाग् उदगायत् ।
यो वाचि भोगस् तं देवेभ्य आगायत् ।
यत् कल्याणं वदति तद् आत्मने ।
ते ऽविदुर् अनेन वै न उद्गात्रात्येष्यन्तीति ।
तम् अभिद्रुत्य पाप्मनाविध्यन् ।
स यः स पाप्मा यद् एवेदम् अप्रतिरूपं वदति ।
स एव स पाप्मा ॥

te ha vācam ūcus tvaṃ na udgāyeti ।
tatheti tebhyo vāg udagāyat ।
yo vāci bhogas taṃ devebhya āgāyat ।
yat kalyāṇaṃ vadati tad ātmane ।
te ’vidur anena vai na udgātrātyeṣyantīti ।
tam abhidrutya pāpmanāvidhyan ।
sa yaḥ sa pāpmā yad evedam apratirūpaṃ vadati ।
sa eva sa pāpmā ॥

They said to speech (Vâk): 'Do thou sing out for us (the udgîtha).' 'Yes,' said speech, and sang (the udgîtha). Whatever delight there is in speech, that she obtained for the Devas by singing (the three pavamânas); but that she pronounced well (in the other nine pavamânas), that was for herself. The Asuras knew: 'Verily, through this singer they will overcome us.' They therefore rushed at the singer and pierced her with evil. That evil which consists in saying what is bad, that is that evil.

F. Max Müller · The Upanishads, Sacred Books of the East 15 (1884)