Judges 16:9
Now there were men lying in wait, abiding with her in the chamber. And she said unto him, The Philistines be upon thee, Samson. And he brake the withs, as a thread of tow is broken when it toucheth the fire. So his strength was not known.
With Philistine men lying in wait nearby in the chamber, Delilah announces their attack upon Samson and he snaps the withs as easily as a thread of tow breaking when it touches fire, so the source of his strength remains unknown. That strength lasted while his Nazarite vow was unbroken, depending on his Nazarite condition symbolized by his unshorn hair rather than simply on his physical build. His repeated escapes in this same setting gave him clear warning that Delilah was conspiring with his enemies, yet he continued to expose himself to danger.
The verse belongs to the account of his ruin: though a mighty Israelite ruler under a lifelong Nazarite vow whom God could have used for His glory, he became infatuated with a wicked woman, broke his sacred pledge, and betrayed the secret of his strength, the defense of Israel, into Philistine hands. Through her influence and deceit, Satan sought to destroy him and remove the mysterious strength that intimidated Israel's enemies, showing the power of woman enlisted in Satan's service to entrap and destroy souls, by which many wounded have been cast down and many strong men slain. His extraordinary physical strength did not mean moral self-control; his failure came from letting passion control him instead of relying on God's strength and obeying God's law, and his choices led toward shame, disaster, and death.
Giving to her the love and service due to God was idolatry; he lost his sense of God's sacred work and, blind to sin and captive to it, sacrificed honor, conscience, reputation, strength, usefulness, and other valuable interests to passion and sinful indulgence. The verse illustrates Delilah's power to deceive Samson to his destruction, showing how a person blinded to Satan's work can be deceived and destroyed by lust and fail to discern genuine love from fleshly lust, which must never be mistaken for the love of Christ. It illustrates the danger of allowing a wife to become a snare like Delilah: as his strength failed through entanglement with her, a person who puts his wife before God will go farther from God and become weaker.