長阿含經 7.p96

7.p96

Kāśyapa said to the priest, “Now, I’ll ask you a question and you tell me what you think. Suppose someone weighs iron. First, they weigh it while it’s cold, and later they weigh it while it’s hot. When would it be glowing with color, flexible, and lighter? When would it not be glowing, solid, and heavier?”