Bhagavad Gita
2.69

या निशा सर्वभूतानां तस्यां जागर्ति संयमी | यस्यां जाग्रति भूतानि सा निशा पश्यतो मुनेः ||६९||

yā niśhā sarva-bhūtānāṁ tasyāṁ jāgarti saṁyamī yasyāṁ jāgrati bhūtāni sā niśhā paśhyato muneḥ

Translation

What is night for all beings is the time of awakening for the self-controlled; and the time of awakening for all beings is night for the introspective sage.

Interpretation

One of the most poetic verses in the Gita. The ordinary person is asleep to the spiritual reality (which is the true 'day' for the sage), while the sage is asleep to the sensory world (which is the true 'day' for ordinary people). Their orientations are exactly reversed. The sage is awake where others sleep (to the Self) and at rest where others are active (in the world of sense).