Krishna tells Yudhistira about Jarasandha

Yudhistira told Krishna about the conversation that he had had with Narada and about Pandu's wish.
Krishna said he was absolutely fine with Yudhistira performing Rajsuya sacrifice. Along with Yudhistira needed to be aware of the fact that the consent of a hundred thousand kings was needed for this, and they needed to accept Yudhistira's supremacy.
In Magadha, Jarasandha was ruling and he had many followers. Jarasandha's two daughters had been married to Kamsa, Krishna's maternal uncle. Kamsa had died in Krishna's hands. The two wives of Kamsa asked their father to attack Krishna.
Seventeen times Jarasandha attacked Mathura, and every time Krishna and Balarama fought with Jarasandha but were defeated him. When Jarasandha tried attacking for the eighteenth time, Krishna decided Mathura was no longer safe. They moved to Dwaraka. The people who did not go with Krishna to Dwaraka, were made captive my Jarasandha.
Saying this, Krishna said, Yudhistira needed to defeat Jarasandha and free the prisoners. Jarasandha needed to be killed.
Yudhistira said he was fine with that but before killing someone he wanted to try and see if the method of friendship and peace worked, before attacking Bhima disagreed and said it was good to finish him off upfront.
Krishna said he would think of a way of killing Jarasandha and for that he needed Arjuna and Bhima.
Yudhistira said Jarasandha was the reason why Krishna had to flee from Mathura. If this was the power of Jarasandha, then there was no point in performing a sacrifice like that.
Arjuna said No one was immortal and all would have to die one day. It was good to die a hero's death rather than running away.
Yudhistitra asked Krishna to tell more about Jarasandha. Krishna then started telling Yudhistira :

The land of Magadha was ruled by the king Brihadratha. He was a powerful king, married to the two princesses of Kashi. He had no children. Frustrated, he left the kingdom and along with his two wives retired into the forest. As soon he entered the forest, he met the sage Chandakaushika. He prostrated himself in front of the sage and asked for blessings. The sage asked him where he was going. The king said he was frustrated as he had no children and was going to the forest along with his wives. Suddenly a mango fell on the lap of the sage, who was sitting below a mango tree. He gave the mango to the king and asked him to give the fruit to his chief queen. A child would be born to her.

Taking the blessings of the sage, the king returned back. He divided the mango equally among the two queens. The two queens soon were pregnant and gave birth at the same time. Each had given birth to half a child. The queens asked the maids to throw the delivered parts away.

A rakshashi named Jara happened to be passing by. She saw the two parts and put the two, together. The moment they came together, it formed a child and it started crying out.

Jara, who was hungry decided not eat the baby. This would not satisfy her hunger. On the contrary if the king was pleased, he would give her gifts. Changing into a human form, she took the child to the king and told the king all that had happened. The king rewarded Jara and she left. As the child had been joined by Jara, it was named Jarasandha.

When he was of age, Jarasandha was handed the throne of Magadha. He was a very powerful and ruled by force. It was impossible to defeat him in war. The only way to defeat him was to wrestle with him.

Saying this, Krishna said Bhima was capable of defeating Jarasandha. He said would go with Bhima and Arjuna to Magadha and put an end to Jarasandha,