Unluckily

"They say that Ngoc hoang sent a messenger from heaven to men to say that when they reached old age they should change their skins and live for ever, but that when serpents grew old they must die. The messenger came down to earth and said, rightly enough, "When man is old he shall cast his skin; but when serpents are old they shall die and be laid in coffins." So far so good. But unluckily there happened to be a brood of serpents within hearing, and when they learned the doom pronounced on their kind, they fell into a fury and said to the messenger, "You must say it over again and just the contrary, or we will bite you.""