". . . chapters 24-26 form a discrete literary unit within 1 Samuel. Chapters 24 and 26 are virtually mirror images of each other, beginning with Saul's receiving a report about David's latest hiding place (24:1; 26:1), focusing on David's refusal to lift a hand against Saul, the Lord's anointed' (24:6, 10; 26:11), and concluding with the words of a remorseful Saul and his returning home from his pursuit of David (24:17-22; 26:21, 25). The two chapters form a frame around the central chapter 25, where the churlish Nabal functions as an alter ego of the rejected Saul. In addition, divine protection that keeps David from shedding innocent blood runs as a unifying thread through all three chapters."237
Saul, who had disregarded God's Law, became a deadly threat to David (23:19-28). However, David, who regarded God's Law, became a source of life to Saul (23:29-24:22) and to others in Israel (ch. 25).
In the previous section, Saul sought the opportunity to take David's life. In this one (23:29-24:22), given the opportunity to take Saul's life, David spared him.