Judges 16:7-9

7Samson told her, “If they tie me up with seven fresh bowstrings that have not been dried, I will become as weak as any other man.”

8So the lords of the Philistines brought her seven fresh bowstrings that had not been dried, and she tied him up with them. 9While the men were hidden in her room, she called out, “Samson, the Philistines are here!”

But he snapped the bowstrings like a strand of yarn seared by a flame. So the source of his strength remained unknown.