1 Samuel 1:10-11

10While her soul was bitter, she prayed to Adonai and wept.

11So she made a vow and said, “Adonai-Tzva’ot, if You will indeed look upon the affliction of Your handmaid, remember me and not forget Your handmaid, but grant Your handmaid a son, then I will give him to Adonai all the days of his life and no razor will ever touch his head.”