Muṇḍaka Upaniṣad 1.2.10

1.2.10

iṣṭāpūrtaṃ manyamānā variṣṭhaṃ nānyac chreyo vedayante pramūḍhāḥ.
nākasya pṛṣṭhe te sukṛte 'nubhūtvemaṃ lokaṃ hīnataraṃ vā viśanti.

9. Manifoldly living in ignorance, They think to themselves, childishly: "We have accomplished our aim!" Since doers of deeds (_karmin_) do not understand, because of passion (_rāga_), Therefore, when their worlds are exhausted, they sink down wretched. 10. Thinking sacrifice and merit is the chiefest thing, Naught better do they know—deluded! Having had enjoyment on the top of the heaven won by good works, They re-enter this world, or a lower.