SB 5.8.12
kusa-kusuma-samit-palasa-phala-mulodakany aharisyamano vrkasala-vrkadibhyo bhayam asamsamano yada saha harina-kunakena vanam samavisati.
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
When Maharaja Bharata wanted to enter the forest to collect kusa grass, flowers, wood, leaves, fruits, roots and water, he would fear that dogs, jackals, tigers and other ferocious animals might kill the deer. He would therefore always take the deer with him when entering the forest.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
How Maharaja Bharata increased his affection for the deer is described herein. Even such an exalted personality as Bharata Maharaja, who had attained loving affection for the Supreme Personality of Godhead, fell down from his position due to his affection for some animal. Consequently, as will be seen, he had to accept the body of a deer in his next life. Since this was the case with Bharata Maharaja, what can we say of those who are not advanced in spiritual life but who become attached to cats and dogs? Due to their affection for their cats and dogs, they have to take the same bodily forms in the next life unless they clearly increase their affection and love for the Supreme Personality of Godhead. Unless we increase our faith in the Supreme Lord, we shall be attracted to many other things. That is the cause of our material bondage.