RichThesaurus
at a loss for words
vs
unable to believe one's eyes
at a loss for words
prep
Having nothing to say; not knowing what to say; stunned to the point of being speechless.
unable to believe one's eyes
How often have the words
at a loss for words
and
unable to believe one's eyes
occurred in a corpus of books?
(source:
Google Ngram Viewer
)