וְהָאֹרֵ֗ב יֹשֵׁ֥ב לָהּ֙ בַּחֶ֔דֶר וַתֹּ֣אמֶר אֵלָ֔יו פְּלִשְׁתִּ֥ים עָלֶ֖יךָ שִׁמְשׁ֑וֹן וַיְנַתֵּק֙ אֶת־הַיְתָרִ֔ים כַּאֲשֶׁ֨ר יִנָּתֵ֤ק פְּתִֽיל־הַנְּעֹ֙רֶת֙ בַּהֲרִיח֣וֹ אֵ֔שׁ וְלֹ֥א נוֹדַ֖ע כֹּחֽוֹ׃
當時有埋伏的人為她在內室裡等候。大利拉對參孫說：「參孫哪，非利士人來捉你了！」參孫就掙斷了那些細繩，好像麻線一挨近火就斷了一樣。這樣，他的力氣仍不為人所知。
Rashi
The source of his strength was not revealed. It was not necessary for him to exert himself when he snapped them.