After hearing his story, everyone was chilled to the bone.
Tips
history
From 《史记·酷吏列传》: the Han official Yi Zong executed over four hundred prisoners in a single day, and afterwards the whole commandery '不寒而栗' — shivered though not cold. The story fixed the idiom's emphasis on terror rather than cold.
memory
栗 (lì) here is the verb 'to tremble' (not the chestnut). 不寒而栗 = 'not cold, yet trembling' — shivering purely from fear.