Judges 16:8-9

Then the lords of the Philistines brought up to her seven green withes which had not been dried, and she bound him with them. Now she had liers-in-wait abiding in the inner chamber. And she said unto him, The Philistines are upon thee, Samson. And he brake the withes, as a string of tow is broken when it toucheth the fire. So his strength was not known.