俱舍論頌疏論本 12.43

12.43

問：「第四靜慮何為外災耶？」答：「頌言『四無不動故。』彼無外災，離內災故，由佛說彼名不動地故，內外三災所不及故。」

Question: 'What is the external calamity for the fourth dhyāna?' Answer: 'The verse says, "Because the fourth is immovable, it has none." It has no external calamity because it is free from internal calamities; since the Buddha declared it to be the immovable stage, the three calamities, both internal and external, cannot reach it.'