SB 9.4.48
prag distam bhrtya-raksayam
purusena mahatmana
dadaha krtyam tam cakram
kruddhahim iva pavakah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
As fire in the forest immediately burns to ashes an angry snake, so, by the previous order of the Supreme Personality of Godhead, His disc, the Sudarsana cakra, immediately burnt to ashes the created demon to protect the Lord’s devotee.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
As a pure devotee, Maharaja Ambarisa, although in such danger, did not move an inch from his position, nor did he request the Supreme Personality of Godhead to give him protection. He was fixed in understanding, and it was certain that he was simply thinking of the Supreme Personality of Godhead in the core of his heart. A devotee is never fearful of his death, for he meditates on the Supreme Personality of Godhead always, not for any material profit, but as his duty. The Lord, however, knows how to protect His devotee. As indicated by the words prag distam, the Lord knew everything. Therefore, before anything happened, He had already arranged for His cakra to protect Maharaja Ambarisa. This protection is offered to a devotee even from the very beginning of his devotional service. Kaunteya pratijanihi na me bhaktah pranasyati (Bg. 9.31). If one simply begins devotional service, he is immediately protected by the Supreme Personality of Godhead. This is also confirmed in Bhagavad-gita (18.66): aham tvam sarva-papebhyo moksayisyami. Protection begins immediately. The Lord is so kind and merciful that He gives the devotee proper guidance and all protection, and thus the devotee very peacefully makes solid progress in Krsna consciousness without outward disturbances. A serpent may be very angry and ready to bite, but the furious snake is helpless when faced by a blazing fire in the forest. Although an enemy of a devotee may be very strong, he is compared to an angry serpent before the fire of devotional service.