Elisabeth Elliot records the following apocryphal tale in order to expose the misguided mindset of doing the right things for the wrong reasons.
[Jesus said to his disciples,] “I’d like you to carry a stone for me.” He didn’t give any explanation. So the disciples looked around for a stone to carry, and Peter, being the practical sort, sought out the smallest stone he could possibly find. After all, Jesus didn’t give any regulation for weight and size! So he put it in his pocket. Jesus then said: “Follow Me.” He led them on a journey. About noontime Jesus had everyone sit down. He waved his hands and all the stones turned to bread. He said, “Now it’s time for lunch.” In a few seconds, Peter’s lunch was over. When lunch was done Jesus told them to stand up. He said again, “I’d like you to carry a stone for me.” This time Peter said, “Aha! Now I get it!” So he looked around and saw a small boulder. He hoisted it on his back and it was painful, it made him stagger. But he said, “I can’t wait for supper.” Jesus then said: “Follow Me.” He led them on a journey, with Peter barely being able to keep up. Around supper time Jesus led them to the side of a river. He said, “Now everyone throw your stones into the water.” They did. Then he said, “Follow Me,” and began to walk. Peter and the others looked at him dumbfounded. Jesus sighed and said, “Don’t you remember what I asked you to do? Who were you carrying the stone for?”
—From Elisabeth Elliot’s, These Strange Ashes: Is God Still in Charge?