1 Samuel 1:11-13

And she vowed a vow and said, “O LORD of hosts, if you will indeed look on the affliction of your servant and remember me and not forget your servant, but will give to your servant a son, then I will give him to the LORD all the days of his life, and no razor shall touch his head.” As she continued praying before the LORD, Eli observed her mouth. Hannah was speaking in her heart; only her lips moved, and her voice was not heard. Therefore Eli took her to be a drunken woman.