Maandavya Muni gave Shaap to Yam Raaj that he had to born as a Shoodra on Prithvi for 100 years ...

Once King's servants caught some thieves at the Aashram of Maandavya Muni. They thought that Maandavya Muni was also in the group of thieves, so they caught him also and took all of them to the King. The King assigned death punishment to all. So his people put all of them on stake. Since the King's servants brought him while he was doing Tap, he did not feel the slightest touch of the stake. But it happened so that a Pativrataa wife was carrying her leper husband to a prostitute's house, his leg hit him and he woke up from his Tap. He asked the servants to bring him down from the stake. The servants told this to the King, so when he came to know about Maandavya Muni, that he was a Rishi, he immediately called him back.

When Maandavya Muni was taken to Narak to Yam Raaj, he asked Yam Raaj, "What was my sin to get this punishment?" Yam Raaj said, "You have committed a Paap." "What?" "Once you have pierced a Tiddee (locust) with the tip of a Kush." Muni said - "That I must have done when I was a very little child and unknowingly. And you punished me for that little crime?" Then Muni gave Shaap to Dharm Raaj, "Go, and live in Shoodra Varn on Prithvi for 100 years." So He was born as maid-servant's son as Vidur Jee.

Next he extended the age of a child from 12 years to 15 years to ignore his crime.