When Ishbosheth heard about Abner's death at Hebron, he lost all courage, and his people were paralyzed with fear.
References for 2 Samuel 4:1
Now there were two brothers, Baanah and Recab, who were captains of Ishbosheth's raiding parties. They were sons of Rimmon, a member of the tribe of Benjamin who lived in Beeroth. The town of Beeroth is now part of Benjamin's territory
because the original people of Beeroth fled to Gittaim, where they still live as foreigners.
(Saul's son Jonathan had a son named Mephibosheth, who was crippled as a child. He was five years old when Saul and Jonathan were killed at the battle of Jezreel. When news of the battle reached the capital, the child's nurse grabbed him and fled. But she fell and dropped him as she was running, and he became crippled as a result.)
References for 2 Samuel 4:4
One day Recab and Baanah, the sons of Rimmon from Beeroth, went to Ishbosheth's home around noon as he was taking a nap.
The doorkeeper, who had been sifting wheat, became drowsy and fell asleep. So Recab and Baanah slipped past the doorkeeper, went into Ishbosheth's bedroom, and stabbed him in the stomach. Then they escaped.
But before leaving, they cut off his head as he lay there on his bed. Taking his head with them, they fled across the Jordan Valley through the night.
References for 2 Samuel 4:7
They arrived at Hebron and presented Ishbosheth's head to David. "Look!" they exclaimed. "Here is the head of Ishbosheth, the son of your enemy Saul who tried to kill you. Today the LORD has given you revenge on Saul and his entire family!"
But David said to Recab and Baanah, "As surely as the LORD lives, the one who saves me from my enemies, I will tell you the truth.
Once before, someone told me, 'Saul is dead,' thinking he was bringing me good news. But I seized him and killed him at Ziklag. That's the reward I gave him for his news!
Now what reward should I give the wicked men who have killed an innocent man in his own house and on his own bed? Should I not also demand your very lives?"
So David ordered his young men to kill them, and they did. They cut off their hands and feet and hung their bodies beside the pool in Hebron. Then they took Ishbosheth's head and buried it in Abner's tomb in Hebron.