The period of eighteen years is mentioned several times in the Bible, often symbolizing a significant duration of time in which individuals or groups experience trials, bondage, or preparation. This time frame is used to highlight God's sovereignty, the consequences of sin, and the eventual deliverance or fulfillment of His promises.

1. Judges 3:14 · The Israelites served Eglon, the king of Moab, for eighteen years. This period of subjugation was a result of Israel's disobedience to God, as they did evil in His sight. The oppression by Moab was a divine chastisement intended to bring the Israelites to repentance. Eventually, God raised up Ehud, a deliverer, who freed them from Moabite control.

2. Judges 10:8 · The Israelites were oppressed by the Philistines and the Ammonites for eighteen years. This oppression occurred because the Israelites again did evil in the eyes of the Lord by serving the gods of the surrounding nations. The eighteen-year period of suffering led the Israelites to cry out to God for deliverance, demonstrating the recurring cycle of sin, punishment, repentance, and deliverance in the Book of Judges.

3. Luke 13:11 · In the New Testament, Jesus encounters a woman who had been crippled by a spirit for eighteen years. "And a woman was there who had been disabled by a spirit for eighteen years. She was bent over and could not straighten up at all" . Jesus heals her on the Sabbath, demonstrating His authority over physical and spiritual ailments and challenging the legalistic interpretations of the Sabbath by the religious leaders. This miracle underscores Jesus' compassion and His mission to set captives free.

4. Luke 13:4 · Jesus refers to the eighteen people who died when the tower in Siloam fell. "Or those eighteen who were killed when the tower in Siloam fell on them—do you think that they were more sinful than all the others living in Jerusalem?" . This reference is part of a larger teaching on repentance, where Jesus emphasizes that such tragedies are not necessarily a direct result of individual sin but serve as a reminder of the need for all to repent.

The number eighteen, while not as prominent as other biblical numbers, serves as a reminder of the consequences of sin and the hope of redemption. It highlights periods of trial and the faithfulness of God in delivering His people when they turn back to Him. Throughout these accounts, the emphasis is on God's mercy and the importance of repentance and faith.