An inspiring story that depicts how Asañnga's persistent practice of Dharma, brought him to Tushita Heaven, together with the Maitreya Buddha.
A long time ago, in India, the Abhidharma teaching had been challenged on three separate occasions and was about to disappear. But there was a brahmin nun named Prakāśaśīlã, and she thought, "I have been born as a woman. Because of my low status I cannot myself make the Buddha's doctrine shine forth. So I will couple with men and give birth to sons who can spread the teaching of the Abhidharma."
With a Kşatriya as the father she gave birth to the noble Asañnga, and with a Brahmin to Vasubandhu. As her both sons grew up, they asked what their fathers' work was.
The mother replied, "I did not give birth to you to follow in your father's footsteps. You were born to spread the Buddha's teachings. You must study the Dharma, and become teachers of the Abhidharma."
Vasubandhu went off to Kashmir to study Abhidharma with Sanghabhadra.
While Asanga went to Kukkuțapāda Mountain, where he started to do the practice of the Buddha Maitreya hoping that he might have a vision of him and ask him for instructions. Six years passed, despite his hard meditation, he did even had a single auspicious dream.
"Now it looks as if I will never succeed," he felt discouraged and made a depart. Along the path, he came across a man rubbing an enormous iron bar with a soft cotton cloth.
"What are you trying to do, rubbing like that? ", he asked the man.
The man replied, "I need a needle, so l am making one by rubbing away at this bar.”
Asanga thought, "He'll never make a needle by rubbing that huge bar with a soft piece of cotton. Even if it could be done in a hundred years, will he live that long? If ordinary people make such efforts for so little reason, I can see that I have never really practiced the Dharma with any persistence.”
Thus, he went back to his practice. He practiced for three more years, still with no sign.
"This time I'm quite certain that I can never succeed," he said, and he quitted again. Here, he came last to a rock so high that it seemed to touch the heavens. At its foot, a man was stroking it with a feather dipped in water.
“What are you doing?" asked Asanga.
"This rock is too tall," the man said. "I don't get any sun on my house, which is to the west of it. So I'm going to wear it away till it disappears."
Asanga, with the same thoughts as three years before, went back and practiced for another three years, still without so much as a single good dream.
Now utterly dissapointed, he said to himself, "Now whatever I do I can never succeed!" and set off one more time.
As he was leaving, he came across a bitch with two crippled hind legs and her entire hind quarters crawling with maggots. Nevertheless, she was still full of aggression, and tried to bite him as she dragged herself along on her forelegs, the rest of her body trailing along on the ground behind her.
Asanga was swept by deep, unbearable compassion. Cutting off a piece of his own flesh, he gave it to the bitch to eat. Then he decided that he had to rid her of the worms on her hind quarters. Fearing that he might kill them if he removed them with his fingers, he realized that the only way to do it was with his tongue. But whenever he looked at the whole of the creature's body, so rotten and full of pus, he could not bring himself to do it. So he shut his eyes and stretched out his tongue.
Instead of touching the body of the bitch, his tongue touched the ground.
He opened his eyes and found that the bitch had disappeared. In its place stood Lord Maitreya, surrounded by a halo of light.
"How unkind you are," Asanga cried, "not to have shown me your face all this time!"
"It is not that I have not shown myself. You and I have never been separate. But your own negative actions and obscurations were too intense for you to be able to see me. Because your twelve years of practice have diminished them a little, you were able to see the bitch. Just now, because of your great compassion, your obscurations have been completely purified and you can see me with your own eyes. If you do not believe me, carry me on your shoulder and show me to everyone around!"
As Asanga placed Maitreya Buddha on his right shoulder and went to the market, he asked everyone, "What do you see on my shoulder?"
Everyone replied that there was nothing on his shoulder.
Except one old woman whose perception was slightly less clouded by the habitual tendencies. She said,said, "You are carrying the rotting corpse of a dog."
Lord Maitreya then took Asanga to the Tusita heaven, where he gave him The Five Teachings of Maitreya and the other instructions. When he came back to the realm of men, Asanga spread the doctrine of the Great Vehicle widely.
Source: Words of My Perfect Teacher by Patrul Rinpoche