Maitri (Maitrāyaṇīya) Upaniṣad 7.9

7.9

avidyāyāmantare veṣṭyamānāḥ svayaṃ dhīrāḥ paṇḍitaṃ manyamānāḥ |
dandramyamānāḥ pariyanti mūḍhā andhenaiva nīyamānā yathāndhāḥ ||

Brihaspati, having become Sukra, brought forth that false knowledge for the safety of Indra and for the destruction of the Asuras. By it they show that good is evil, and that evil is good. They say that we ought to ponder on the (new) law, which upsets the Veda and the other sacred books. Therefore let no one ponder on that false knowledge: it is wrong, it is, as it were, barren. Its reward lasts only as long as the pleasure lasts, as with one who has fallen from his caste. Let that false science not be attempted, for thus it is said:
(i) Widely opposed and divergent are these two, the one known as false knowledge, the other as knowledge. I (Yama) believe Nakiketas to be possessed by a desire of knowledge; even many pleasures do not move thee.
(2) He who knows at the same time both the imperfect (sacrifice, &c.) and the perfect knowledge (of the Self), he crosses death by means of the imperfect, and obtains immortality by means of the perfect knowledge.
(3) Those who are wrapped up in the midst of imperfect knowledge, fancying themselves alone wise and learned, they wander about floundering and deceived, like the blind led by the blind.