Judges 16:7-9

7Samson said to her, "If they bind me with seven fresh bowstrings that have not been dried, then I shall become weak and be like any other man."

8Then the lords of the Philistines brought up to her seven fresh bowstrings that had not been dried, and she bound him with them.

9Now she had men lying in ambush in an inner chamber. And she said to him, "The Philistines are upon you, Samson!" But he snapped the bowstrings, as a thread of flax snaps when it touches the fire. So the secret of his strength was not known.