SB 5.8.28
tatrapi ha va atmano mrgatva-karanam bhagavad-aradhana-samihanubhavenanusmrtya bhrsam anutapyamana aha.
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Although in the body of a deer, Bharata Maharaja, due to his rigid devotional service in his past life, could understand the cause of his birth in that body. Considering his past and present life, he constantly repented his activities, speaking in the following way.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
This is a special concession for a devotee. Even if he attains a body that is nonhuman, by the grace of the Supreme Personality of Godhead he advances further in devotional service, whether by remembering his past life or by natural causes. It is not easy for a common man to remember the activities of his past life, but Bharata Maharaja could remember his past activities due to his great sacrifices and engagement in devotional service.