He saw them with their weary feet, Who, used to bliss, in cars should ride, Who ne’er by sorrow should be tried, And, as one mournful look he cast, “Drive on,” he cried, “Sumantra, fast.” As when the driver’s torturing hook Goads on an elephant, the look Of sire and mother in despair Was more than Ráma’s heart could bear.

In plain words: Rama sees his parents, who should be riding in comfort, walking wearily after him. Their despair hurts him like a goad hurts an elephant, so he tells Sumantra to drive on fast.