SB 9.4.47
tam apatantim jvalatim
asi-hastam pada bhuvam
vepayantim samudviksya
na cacala padan nrpah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Taking a trident in his hand and making the surface of the earth tremble with his footsteps, that blazing creature came before Maharaja Ambarisa. But the King, upon seeing him, was not at all disturbed and did not move even slightly from his position.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Narayana-parah sarve na kutascana bibhyati (Bhag. 6.17.28). A pure devotee of Narayana is never afraid of any material danger. There are many examples of devotees such as Prahlada Maharaja, who was tortured by his father but was not at all afraid, although he was only a five-year-old boy. Therefore, following the examples of Ambarisa Maharaja and Prahlada Maharaja, a devotee should learn how to tolerate all such awkward positions in this world. Devotees are often tortured by nondevotees, yet the pure devotee, depending fully on the mercy of the Supreme Personality of Godhead, is never disturbed by such inimical activities.