One verse

Srimad Bhagavatam 9.11.18

9.11.18

तत ऊर्ध्वं ब्रह्मचर्यं धार्यन्नजुहोत् प्रभु: । त्रयोदशाब्दसाहस्रमग्निहोत्रमखण्डितम् ॥ १८ ॥

tata urdhvam brahmacaryam dharyann ajuhot prabhuh trayodasabda-sahasram agnihotram akhanditam

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.