The Mukhya Upaniṣads

Maitrī · Prapāṭhaka 1 · Maitrī 1.1

Passage 4

सर्वं चेदं क्षयिष्णु पश्यामो यथेमे दंशमशकादयस्तृणवन्नश्यतयोद्भूतप्रध्वंसिनः ॥१.४ ॥

In plain words

And we see that all this is perishing, as are these gnats and flies and the rest, which are destroyed like grass, coming to be and passing away.