Once upon a time a man was walking beside a wide river. He was meditating on the law of the Lord, for he believed that if he kept his mind fixed on spiritual thoughts all the time, he would achieve perfection.

Just then his thoughts were broken by the sound of a chant used in his religion to prepare for experiencing the Presence of God. This man was a very religious man and so he was angered by what he heard, for the chant was being done wrong. At each transition where you were supposed to sing, “ah-men,” the person was chanting “ā-men (ey-men).”

He knew it was his religious duty to go to the person, probably a hermit living alone on the island in the middle of the river, and instruct him in the correct way to do the chant. You see how very religious and self-sacrificing he was, for he put his religious duty to care for an ignorant hermit ahead of his own quest for perfection.

So, renting a boat, he rowed across the river to the island and found the hermit moving in rhythm to his chant.

“Friend,” he said, breaking the hermit’s concentration, “you are doing the chant wrong. I have come to instruct you in the right way.”

“Thank you,” said the hermit, genuinely grateful for the help he was being offered.

After instructing the hermit, he went away congratulating himself on his good deed. As he rowed back across the river, he recalled the ancient saying, “one who achieves perfection will walk upon the water without fear,” and he dreamed of the day he would be able to walk on the water himself.

His meditation was interrupted, however, by the sound of the hermit’s chant once again. At the first transition there came a faltering “ah-men,” but as the chant progressed the hermit lapsed back into his old habits, saying “ā -men” over and over again. You can imagine how disgusted he was with the hermit. His thought about the ignorance of human beings and their persistence in error were interrupted suddenly by a strange sight. The hermit was coming toward him—walking on the water.

“I’m sorry to bother you again,” said the hermit as he approached the boat,” but I have forgotten the right way to say the chant. Would you be so good as to instruct me once more?”

~ from Spiritual Dimensions of Pastoral Care by Editors Borchert and Lester.
There are many versions of this tale.