The Things They Carried Chapter 6, Friends
Jensen and Strunk slowly learn to trust each other. They even make up a written pact that says that if one of them gets seriously injured, the other will kill him. Then Strunk steps on a mine, and his leg is blown away at the knee. He looks up at Jensen and frantically begs him not to kill him. Jensen assures him that he won't, and Strunk passes in and out of consciousness, asking Jensen not to kill him over and over. Strunk is taken away and dies soon after. Jensen seems relieved.