singing...more

But it is said that nama sankeertan will put in hell those who abuse it!
So what is the abuse?
There is a long list … well may be ten points. Some are: talking ill of sadhus; seeing a difference between Shiva and Vishnu (in essence between various deities); thinking as one has the strength of nama sankeertan one can do acts proscribed. For more information have a look at Narada bhakti sutra.

It is not even essential to “sing”! (Wow, that saves a lot of people nearby!) It is enough to utter His name. A story that illustrates this is the story of Ajamila. He was a first rate sinner. There was no sin that he had not committed. In death bed he called to his son to give him a final word. It so happened that the son's came was Narayanan. As he uttered the word Narayana his life ended. The yama dhootas (servants of the death lord) came to take him away. But they were intercepted by the Lord Narayana's servants. Claiming since uttering the word narayana qualified him to be among the Vishnu bhaktas he was taken to vaikuntha – the abode of Sri Narayana.
That does not mean wee can utter his name just once and be saved forever!
A disciple of Sri Ramakrishana asked him once: If one bathes in the Ganges one's sins are washed away. I see so many bathe in Ganges everyday and still see no change in them!
To this jokingly Ramakrishna replied: as one approaches the ganges the wind carries the droplets and that chases away the sins. But where will they go? They take refuge in the trees and other plants nearby. Having bathed one returns and on the way there are so many shops. As soon as one sees them the mind starts craving for things and having found the weakness his sins come back to him!