What was David’s action toward the murderers of Ish-bosheth?

The answer to this question can be found in 2 Samuel, chapter 4. This particular story begins by introducing readers to Rekab and Baanah and listing a bit about their lineage. The important part of all of the information is that they are supposedly faithful to Ish-Bosheth. Rekab and Baanah arrived at Ish-Bosheth's house during the heat of the day, and they found the man resting. Rekab and Baanah stabbed Ish-Bosheth in the stomach and cut off his head. They brought the head to David, and they likely thought they would receive some kind of reward. Unfortunately for Rekab and Banaah, David was greatly angered by their actions. He accused them of killing an innocent man.

How much more—when wicked men have killed an innocent man in his own house and on his own bed—should I not now demand his blood from your hand and rid the earth of you!

David's anger doesn't end well for these two men. David has them killed. Additionally, their hands and feet are cut off, and their bodied are put on display by the pool in Hebron.