तत ऊर्ध्वं ब्रह्मचर्यं धार्यन्नजुहोत्प्रभुः ।
त्रयोदशाब्दसाहस्रम् अग्निहोत्रमखण्डितम् ॥ १८ ॥
tata urdhvam brahmacaryam
tatah-thereafter; urdhvam-after mother Sita's going into the earth; brahmacaryam-complete celibacy; dharayan-observing; ajuhot-performed a ritualistic ceremony and sacrifice; prabhuh-Lord Ramacandra; trayodasa-abda-sahasram-for thirteen thousand years; agnihotram-the sacrifice known as Agnihotra-yajna; akhanditam-without ceasing.
After mother Sita entered the earth, Lord Ramacandra observed complete celibacy and performed an uninterrupted Agnihotra-yajna for thirteen thousand years.