Maharaja Ambarisha had brother who was very very sinful. Ambarish tried to preach to him, but with no success. So he asked Narada Muni to preach to his brother. Narada did not want to, but finally he reluctantly agreed.
When Narada came to see the sinful Raja, he was first greeted with respect, but upon hearing preaching words of Narada Muni, Raja started to scream and to throw wine’s bottles at Narada. So Narada had to escape, but from a distance he shouted to Papa-Raja (sinful king) “When you will be in front of Yamaraj (lord of death ), just ask him this one question -
"What is the result of having sadhu sanga for a lava-matra (a moment’s association with a pure devotee of God)"?
After death, Papa-Raja was certainly taken to Yamaraja’s court. Upon hearing from Citragupta about sins committed by Papa-raja, Yamaraja felt compassion and he said – "You will certainly be thrown to hell for an eternity, but I can fulfill your last request now, what do you want"?
Hearing such words, Papa – raja recollected Narada's advice and said – "Could you tell me what is the result of having sadhu sanga for lava matra"?
Yamaraj became amazed. He said – "I’m sorry, but here we deal with sinners, not with sadhus, so i don’t know the answer, but since I’ve promised to fulfill your last desire, I’ll take you to Lord Brahma and he will answer your question.
And so they flew to Brahmaloka. Upon hearing such and elevated question, Lord Brahma said – "I’m sorry, I am too busy with my creation, and pure sadhus are not subject to the rules of my creation. You'll have to go to see Lord Siva."
When they arrived on Lord Siva's planet, Siva, after hearing what’s the matter, said – "How can I answer such question?, I am too busy with such ghastly creatures who follow me, I do not deal with sadhus, you will have to ask Lord Narayan himself."
After that, they approached Lord Narayan in Vaikuntha. Hearing such a nice question the Lord smiled and said – "The result is -- that one is delivered to Vaikuntha by all means. And because you have already brought him here, he will stay, and you my dear servants, can go back to do your duties. Thank you."
Such is a result of lava matra sadhu sanga