take somebody at their 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 somebody at their ˈword

believe exactly what somebody says or promises: She said I could go and stay with her in Paris whenever I wanted, so I took her at her word.
See also: somebody, take, word