Judges 16:17-19

17Then [finally] he told her everything that was in his heart and said to her, “A razor has never been used on my head, for I have been a Nazirite to God from my mother’s womb. If I am shaved, then my strength will leave me, and I will become weak and be like any [other] man.”

18Then Delilah realized that he had told her everything in his heart, so she sent and called for the Philistine lords, saying, “Come up this once, because he has told me everything in his heart.” Then the Philistine lords came up to her and brought the money [they had promised] in their hands.

19She made Samson sleep on her knees, and she called a man and had him shave off the seven braids of his head. Then she began to abuse Samson, and his strength left him.