Explanation
(a) David's hiding place was revealed to Saul by the Ziphites and Saul went with three thousand troops of Israel to seek David in the Wilderness of Ziph. David sent out spies to know if it was true that Saul had come after him. He asked for volunteers to accompany him. At night, David and Abishai went to Saul's camp and found Saul sleeping within the encampment with his spear stuck to the ground. Abishai asked for permission to slay Saul, but David refused because the Lord forbids anyone to kill the Lord's anointed. However, he took Saul's spear and bottle (Jar) of water and went away. No man saw them (David and Abishai) because a deep sleep from the Lord had fallen upon them. From a far distance, David called upon Abner and condemned his incompetence. Saul recognized David's voice. David pleaded his innocence to Saul and Saul repented, saying, I have done wrong; return my son, David for I will no more do you harm. David gave back Saul's spear through one of Saul's men and prayed for Saul. Saul blessed David and they returned to their respective homes.
(b) From the account of how David spared Saul's life, a lot has to be learnt. These include:
(i) Readiness to forgive.
(ii) Recognition / acceptance of our fault
(iii) Respect for authorities
(iv) Respect for God's word / instruction
(v) God protects His own; for instance, He caused sleep upon David's enemies.