Valmiki Ramayana Ayodhya Kanda Sarga 63 Shloka 2
Original Shlokaरामलक्ष्मणयोश्चैव विवासा द्वासवोपमम्। आविवेशोपसर्गस्तं तम स्सूर्यमिवासुरम्।।2.63.2।।
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रामलक्ष्मणयोः Rama and Lakshmana, विवासात् due to banishment, वासवोपमम् like Indra, तम् him, असुरम् relating to that asura, तमः darkness, सूर्यमिव like the Sun, उपसर्गः great calamity, आविवेश took possesion of.
Indralike Dasaratha due to banishment of Rama and Lakshmana, was besieged by a great calamity like the Sun enveloped by demonic dark at the time of eclipse.