This is a Tibetan story by Anam Thubten Rinpoche as retold by Barbara Helen Berger. I found it in Parabola: Tradition, myth and the search for meaning, Vol.32; Issue 1.
Once there was a humble ani, a nun, who loved the enlighten lady Tara* with all her heart. Ever day when the sun was rising over the mountains she climbed up to her rooftop. There in a loud voice, with palms together, she chanted her prayer to Tara. And the man who lived next door couldn’t help hut hear it.
He winced as if the sound hurt his ears. The ani chanted the prayer with so many mistakes. She never got all the words right. She even left some out. The man was a scholar and knew very well how the prayer ought to be done. Yet he was puzzled. For every day in the light of the rising sun, he saw the glorious Tara herself limping to the roof next door.
How amazing, he thought, how strange that Tara was coming to visit the ignorant ani. Why was she limping? Surely it must be due to all the mistakes in the prayer.
So he went next door and the ani greeted him with a smile. The scholar said, “I am sorry, but you are not chanting to Tara properly. You are doing it wrong.”
The smile fell from the ani’s face. Her eyes filled with tears.
“Don’t worry,” the man said, “I can teach you.”
So the ani tried hard to learn, little by little, until at last she was able to say each syllable right, each word in the proper order, leaving nothing out. Then every morning, the scholar was pleased to hear her chanting without a single mistake.
After a while, he noticed that Tara never came to visit the ani anymore. He puzzled over this. Finally he went next door.
Greeting the ani with palms together he said, “I am the one who made a big mistake. Please go back to chanting as you did before.”
So she did. Joyfully, the ani prayed as she always had. Her face shone with devotion. She sand out in a loud voice with her whole heart. She didn’t say all the words right. She even left some out. But know the scholar heard only a voice of pure faith. And sure enough, every day in the light of the rising sun he saw the glorious Tara herself come limping** back again.
* Tara is also called the great compassionate mother, the embodiment of wisdom and the great protectress.
** Tara limps because “the story is not meant to excuse our own sloppiness or lack of knowledge, but to assure us that a pure and deeply felt intention is always stronger”.