1 Samuel 1:11-13

11And she made a vow, saying, “O LORD of Hosts, if only You will look upon the affliction of Your maidservant and remember me, not forgetting Your maidservant but giving her a son, then I will dedicate him to the LORD all the days of his life, and no razor shall ever touch his head.”

12As Hannah kept on praying before the LORD, Eli watched her mouth. 13Hannah was praying in her heart, and though her lips were moving, her voice could not be heard.

So Eli thought she was drunk