Yudhisthira faints after returning from offering jalatharpana to Bheeshma, . Both Dhritharashtra and Krishna help him recover and urge him to take courage; Krishna is in fact a bit stern with Yudhisthira. But Yudhisthira is still distraught; tells Krishna that he feels like giving up everything and going to the forest. He then asks if there is some way he can atone for his sins and clear his mind.
Vyasa, who is present there, tells Yudhisthira that he is confused and asks, 'Is it really possible that a man can act independently and do as he pleases? Whether it is good or bad, Ishwara sets it in motion and man just implements it. But if you really think that you have committed a sin, there are ways to atone for it. People who have been wicked are known to perform yagna, penance and give charity to purify themselves. Devatas became strong with this practice and were able to defeat the demons. You can perform Ashwamedha Yagna the way Srirama and Bharatha chakravarty had done earlier and give away plenty of food and money.'
Yudhisthira agrees that Ashwamedha saves the world itself from sins, but has a problem. 'Where will I get the money for this? I do not have the heart to ask my brothers to go and get it for me. With so many kings dead, from where do I get tributes? The treasury of the kauravas is empty and ashwamedha costs money. Even if I pledge the earth it will not be enough!'
Vyasa gives him a solution, 'Previously, the Maruttha king had performed the yagna in the himalayas. There is still a lot of money lying there as the brahmins could not transport it. You can arrange to get it, there is enough for you!'
With this news Yudhisthira calms down and get busy with ruling his kingdom.
There is a note from the author that he is not including 'Anugita' which is part of this parva.
'It contains Krishna's conversation with Arjuna when Krishna decided to
return to Dwaraka after restoring to the Pandavas, their kingdom. The
main topics discussed are transmigration of souls, means of attaining liberation, description of gunas and ashramas, dharma, and the effects of tapas or austerity.'
There is one more link: THE ANUGITA
BEING A TRANSLATION OF SANSCRIT MANUSCRIPTS FROM THE ASVAMEDHA PARVAN OF THE MAHABHARATA, AND BEING, A NATURAL ADJUNCT TO THE BHAGAVAD-GITA,
KASHINATH TRIMBAK TELANG, MA, LL.B.
My curiosity took me back to wikipedia about ashwamedha yagna:
There is more to it than just letting a horse to wander for a year! There is a role for the queens in this sacrifice. I guess I will let you read about it by yourself !