Valmiki Ramayana Aranya Kanda Sarga 16 Shloka 8
Original Shlokaसेवमाने दृढं सूर्ये दिशमन्तक सेविताम्। विहीनतिलकेव स्त्री नोत्तरा दिक्प्रकाशते।।3.16.8।।
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सूर्ये Sun, अन्तकसेविताम् serving the god of death, दिशम् direction, दृढम् stand still, सेवमाने attending, उत्तरा दिक् northern side, विहीनतिलका without the vermilion mark, स्त्रीव like a woman, प्रकाशते is shining.
As the Sun has resorted to the direction (south) that serves the god of death, the north devoid of (the Sun) shines like a woman without the vermilion mark on the forehead.