The Pilgrim's Progress (John Bunyan)

When the Interpreter had done, he takes them out into his garden again, and had them to a tree whose inside was all rotten and gone, and yet it grew and had leaves. Then said Mercy, "What means this?" "This tree," said he, "whose outside is fair, and whose inside is rotten, it is to which many may be compared that are in the garden of God; who with their mouths speak high in behalf of God, but indeed will do nothing for him; whose leaves are fair, but their heart good for nothing but to be tinder for the devil's tinder-box."

Pg. 240-241