Judg 16:9

וְהָאֹרֵ֗ב יֹשֵׁ֥ב לָהּ֙ בַּחֶ֔דֶר וַתֹּ֣אמֶר אֵלָ֔יו פְּלִשְׁתִּ֥ים עָלֶ֖יךָ שִׁמְשׁ֑וֹן וַיְנַתֵּק֙ אֶת־הַיְתָרִ֔ים כַּאֲשֶׁ֨ר יִנָּתֵ֤ק פְּתִֽיל־הַנְּעֹ֨רֶת֙ בַּהֲרִיח֣וֹ אֵ֔שׁ וְלֹ֥א נוֹדַ֖ע כֹּחֽוֹ׃

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.