You can read a previous post that parallels this passage here: 1 Samuel 31
1 and 2 Chronicles were written to elaborate on the reign of David and show that his dynasty was ordered and directed by God. In 1 Chronicles 10 and 11, the chronicler contrasts the illustrious beginning of David's reign with the tragic ending of Saul's reign (Saul's reign and dynasty was 40 years from 1051-1011 B.C. while David's dynasty lasted 425 years from 1011-586 B.C.).
This narrative is practically identical to 1 Samuel 31 with the exception that the author adds that the Philistines hung Saul's head in the temple of Dagon (1 Chronicles 10:10) but omits that they hung his body on the wall of Beth Shan (1 Samuel 31:10). In addition, the 1 Chronicles account has a theological observation about Saul's death:
REFLECTION and APPLICATIONSo Saul died for his trespass, which he committed against the LORD, because of the word of the LORD which he did not keep (1 Samuel 13:13-14;15:23); and also because he asked counsel of a medium (1 Samuel 28:7), making inquiry of it, and did not inquire of the LORD. Therefore He killed him and turned the kingdom to David the son of Jesse. (1 Chronicles 10:13-14)
Saul did not obey God's commands and did not finish well. Jesus has some words for those who do obey:
I want to have God's commandments and keep them. How about you?He who has My commandments and keeps them is the one who loves Me; and he who loves Me will be loved by My Father, and I will love him and will disclose Myself to him. (John 14:21)
Lord, help us to finish WELL by treasuring Your Word and obeying You. We pray this in Jesus' name. Amen.