One day King Dasaratha assembled his ministers and sage Vasishta in his court and sought their counsel regarding his son's marriage. The palace guard entered and announced the arrival of sage Viswamitra.The King and his ministers immediately went to the palace gate to receive the sage. He was given a royal welcome and treated with due respect. The King expressed his happiness and promised to give the sage whatever he wanted. Viswamitra explained the reason for his arrival. He informed the King that he was performing a Yaga (sacrifice) and that the Demons Mareesan and Subahu were pouring blood and flesh into the fire thereby disrupting the Yaga. He requested the King to send Rama with him so that he can kill the Demons. 

But King Dasaratha did not have the heart to part with his son and so he offered himself in the place of Rama to help the sage. Viswamitra refused his help and insisted on taking Rama. King Dasaratha was unrelenting and so the sage became furious and addressed the King thus," Oh King of Kakuthstha vamsa! You, who gives promises and later goes back on them, live happily with your family and relatives".

Sage Vasishta on hearing this became agitated and went to the King to explain the dharmas,and the greatness of Viswamitra. He told the King that Viswamitra stood foremost in the knowledge of Asthras and that he can kill the demons on his own. It was for Rama's own good that the sage is requesting his help, Vasishta reasoned. Finally Dasaratha agreed and Lakshmana who always followed Rama decided to join him too. Both Rama and Lakshmana saluted their father and with their bows and arrows and accompanied Viswamitra to fulfill the promise.

They reached the River Sarayu and Viswamitra communicated two Mantras called 'Palai' and 'Adhipalai' to them. He told them that by chanting these two mantras one will not feel hungry,thirsty or tired and remain untouched by diseases. They spent the night there and crossed the river in the morning to reach a forest. Rama asked Viswamitra about the forest and Viswamitra informed him about the Demoness Thataka, who killed all living beings in the forest and who attained power after doing penance from Lord Bhrama. She turned into a Demoness by the curse of sage Agasthya and Viswamitra ordered Rama to kill her.