Nagasena Bhiksu Sutra 2.62
T 1670B Nāgasena Bhikṣu Sūtra
Part 2: Dialogues 2.62. The Power of Single Mindfulness of the Buddha
The king asked Nāgasena again, “Your monks say, ‘If anyone who does evil deeds in the world for a hundred years, at the time of dying, he will be reborn in heaven after death if he has even one thought of the Buddha.’ These words I cannot believe. Again they say, ‘He who should take the life of a living being would fall into the hells.’ These words I cannot believe either.”
Nāgasena asked the king, “Suppose a man were to put a small stone into the water. Would the small stone float on the surface of the water or sink into the water?”
“The small stone would sink.”
“If a hundred large stones were put into a boat, would the boat sink?”
“No, it would not sink.”
Then Nāgasena said, “As a hundred large stones in a boat would not sink, a man with one thought of the Buddha will not fall into the hells, but be born in the heavens even though he had done evil deeds in the past. The small stone that sinks is like people who do evil, but do not know the Dharma of the Buddha. When they die they will fall into the hells.”
“Excellent, Nāgasena.”