Definition
An expression used in response to a statement to challenge its validity, often conveying skepticism or disagreement.
谁说的？
"This restaurant is the best in town?" Says who?
「这家餐厅是城里最好的？」谁说的？
"Everyone agrees," Says who? I certainly don't!
「大家都同意。」谁说的？我当然不同意！
"You should always listen to your elders." Says who? I think I should make my own decisions.
「你应该总是听从长辈的话。」谁说的？我认为我应该自己做决定。