अस्तमित आदित्ये याज्ञवल्क्य किंज्योतिरेवायं पुरुष इति ।चन्द्रमा एवास्य ज्योतिर्भवतीति ।चन्द्रमसैवायं ज्योतिषास्ते पल्ययते कर्म कुरुते विपल्येतीति ।एवमेवैतद्याज्ञवल्क्य ॥४,३.३ ॥
In plain words
"When the sun has set, Yājñavalkya, what light does this person have?" "The moon becomes his light. With the moon as his light he sits, moves about, does his work and returns." "So it is, Yājñavalkya."
The commentators
Bṛhadāraṇyakopaniṣadbhāṣyam· avatāraṇikā
तथा अस्तमिते आदित्ये, याज्ञवल्क्य, किंज्योतिरेवायं पुरुष इति- चन्द्रमा एवास्य ज्योतिः ॥
In plain words
In the same way: once the sun goes down, Yājñavalkya, what does a person live by then? The moon -- the moon becomes his light.
Close to the Sanskrit
Likewise: "When the sun has set, Yājñavalkya, what light does this person then have?" -- "The moon indeed is his light."