This story comes from Bhagavat Purana, this story tells us that just by reciting name of God one can attain Moksha or salvation .
Ajamila was a Brahmin married man, obedient to his father and wife. One day he went to forest, where he saw a woman singing and dancing. He fell in infaction with her beauty and wanted to have her. So
She was a prostitute, but Ajamila could not control himself. So, he married this woman and left his wife and family.
He started getting involved in many bad activities such as robbery, ransom, gambling etc. Through all these activities he was supporting his new family. Out of this prostitute he had ten sons.
He was fond of his last son, whom he named Narayan. When he grew old, he would constantly calling out Narayan, Narayan to his son. His son being young would not listen and keep playing with his friends.
On his death bed he saw Yama dutas coming to take his soul. He called out to his son Narayan in fear. At this point Vishnu dutas came for his soul. And then they exchanged dialogue with Yama dutas regarding recitation of God's name.
The Vishnu dutas explained that the Shastras state that the mere utterance or the recitation of the name of Vishnu, even if taken to denote another person, or in a friendly joke, or as an insertion during the recitation of a song, or even as an apparent insult, completely annihilates all the sins of the one who utters it. Ajamila, who witnessed the exchange between the beings, fell into remorse, announcing that he had indeed led a vile life and unworthy of his Brahminhood, and would henceforth lose his sense of self in his service to Vishnu. By this manner, the Brahmana Ajamila, who had neglected his duties and led a sinful life, was able to achieve moksha, and attain Vaikuntha.
