While 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.
Jewish Publication Society of America Version (JPS1917) - Judges 16:9 >Now she had liers-in-wait abiding in the inner chamber. And she said unto him: 'The Philistines are upon thee, Samson.' And he broke the bowstrings as a string of tow is broken when it toucheth the fire. So his strength was not known.