When Eli saw Hannah's lips moving silently in prayer, what did he think?

Answer: That she was drunk

Eli said, "Put away your wine!" Hannah replied that she had not been drinking but was pouring out her soul before the LORD.

“Hannah was praying in her heart, and though her lips were moving, her voice could not be heard. So Eli thought she was drunk”— 1 Samuel 1:13 (BSB)