तस्य for him, तथा in that manner, गच्छतः एव thus travelling, शिवा auspicious, रजनी night, व्यपायात् ended, (सः he), शिवाम् auspicious, सन्ध्याम् sandhya (morning twilight), उपास्य having worshipped, विषयान्तम् frontiers of the country, व्यगाहत reached.

While Rama was thus travelling, the auspicious night ended. With the sandhya (morning twilight), worship over, he reached the frontiers of the country.