Canto 2 -
Ayodhyā-kāṇḍa
Chapter 39: Kausalyā Instructs Sītā
Text 2.39.28

न मामसज्जनेनार्या समानयितुमर्हति।
धर्माद्विचलितुं नाहमलं चन्द्रादिव प्रभा॥

na mām asaj-janenāryā samānayitum arhati
dharmād vicalituṁ nāham alaṁ candrād iva prabhā

na = not; mām = me; asat-janena = with unchaste women; āryā = the noble lady; samānayitum = equate; arhati = should; dharmāt = from dharma; vicalitum = deviating; na aham alam = I am incapable of; candrāt = [cannot be separated] from the moon; iva = just as; prabhā = a ray of moonlight.

The noble lady should not equate me with unchaste women. I am incapable of deviating from dharma just as a ray of moonlight [cannot be separated] from the moon.1

1 This is clear evidence that Sītā-devī is similar in nature to her husband Lord Rāma, the very personification of dharma.