Srimad Bhagavatam Canto 09, Chapter 11, Text 15

SB 9.11.15

munau niksipya tanayau
 sita bhartra vivasita
dhyayanti rama-caranau
 vivaram pravivesa ha
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Being forsaken by her husband, Sitadevi entrusted her two sons to the care of Valmiki Muni. Then, meditating upon the lotus feet of Lord Ramacandra, she entered into the earth.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
It was impossible for Sitadevi to live in separation from Lord Ramacandra. Therefore, after entrusting her two sons to the care of Valmiki Muni, she entered into the earth.
Srimad Bhagavatam Canto 09, Chapter 11, Text 13-14
Srimad Bhagavatam Canto 09, Chapter 11, Text 16