How can I fail his will to do, Friend, master, grateful sovereign too? One only pang consumes my breast: That his own lips have not expressed His will, nor made his longing known That Bharat should ascend the throne.

In plain words: Rama says he could never refuse his father, who is his friend, master and king. His only pain is that his father did not tell him himself that he wanted Bharata, Rama's brother, to be king.