अस्तमित आदित्ये याज्ञवल्क्य चन्द्र-मस्यस्तमिते किंज्योतिरेवायं पुरुष इत्य-ग्निरेवास्य ज्योतिर्भवतीत्यग्निनैवायं ज्यो-तिषास्ते पल्ययते कर्म कुरुते विपल्येती-त्येवमेवैतद्याज्ञवल्क्य ॥ ४ ॥
In plain words
"And once both the sun and the moon have gone down, Yājñavalkya -- what light does a person live by then?" "Fire becomes his light," he said. "By firelight he sits, walks about, does his work, and comes home again." "Just so, Yājñavalkya. Just so."
Close to the Sanskrit
"When the sun has set, Yājñavalkya, and the moon too has set, what light does this person then have?" "Fire indeed is his light," [he said]. "By that very firelight he sits, goes about, performs work, and returns." "Just so, Yājñavalkya."