1 Samuel 1:11-13

11And 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 to Jehovah all the days of his life, and there shall no razor come upon his head.

12And it came to pass as she continued praying before Jehovah, that Eli marked her mouth.

13Now Hannah spoke in her heart; only her lips moved, but her voice was not heard; and Eli thought she was drunken.