B.G 2.69

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

yā niśā sarvabhūtānāṁ tasyāṁ jāgarti saṁyamī। yasyāṁ jāgrati bhūtāni sā niśā paśyatō munēḥ ॥69॥

Where it is night for all beings, there the self controlled is wide awake. Where the beings are awake, that is observed as night by the meditating monk.

Gīta Tātparya 2.69

The self-controlled who is focussed on Brahman sees only him and nothing else, similar to a person seeing the wonderful object glowing in the night.

"If the supreme Brahman is seen by other than the Dēvas, they don't observe anything else. It is similar to a mesmerized person seeing the wonderful object in the night. Only the Brahman who is in the front is clearly visible, and everything else is not visible, because of their concentration of mind and being immersed in its bliss. The Dēvas, similar to the Sun, may see everything based on their hierarchy."

-stated thus in Brahmatarka.