take at word

take (one) at (one's) word

To accept what one says without further verifying or investigating. Why some people take that pundit at his word is beyond me. He clearly has an ulterior motive. You're right to be wary, but, in this case, I think we can take John at his word. He's just trying to help.
See also: take, word

take at (someone's) word

To be convinced of another's sincerity and act in accord with his or her statement: We took them at their word that the job would be done on time.
See also: take, word