Sukadeva Gosvami compares the steadiness of a devotee to that of a mountain in Srimad Bhagavatam, 10.20.15: “Just as devotees whose minds are absorbed in the Personality of Godhead remain peaceful even when attacked by all sorts of dangers, the mountains in the rainy season were not at all disturbed by the repeated striking of the rain-bearing clouds.”
Unflappability of the Devotees of Krsna