What does the Bible say about the war between the spirit and the flesh?

In 2 Samuel 3:1, we see a vivid depiction of the ongoing war between the house of Saul and the house of David, which serves as an allegory for the conflict between the spirit and the flesh. This conflict is inherent to every believer's life, where the spirit strives for holiness while the flesh resists and rebels against God's authority. The Apostle Paul echoes this in Galatians 5:17, stating that the flesh sets its desires against the spirit, and the spirit against the flesh; these are in opposition to each other.