What does the Bible say about God rejecting Saul?

In 1 Samuel 31, we see the culmination of God's rejection of King Saul, which stemmed from his repeated disobedience and rebellion against God's commands. God had clearly instructed Saul to destroy the Amalekites entirely, but Saul failed to obey, sparing their king and taking the best livestock for himself, resulting in God declaring, 'Because thou hast rejected the word of the Lord, he hath also rejected thee from being king' (1 Samuel 15:23). Saul's choices led to severe consequences not just for him but also for Israel, illustrating that rebellion against God's will always leads to judgment.