1 Samuel 1:10-11

And she was in bitterness of soul, and prayed unto Jehovah, and wept sore. And she vowed a vow, and said, O Jehovah of hosts, if thou wilt indeed look on the affliction of thy handmaid, and remember me, and not forget thy handmaid, but wilt give unto thy handmaid a man-child, then I will give him unto Jehovah all the days of his life, and there shall no razor come upon his head.