rush to conclusions
To draw conclusions, make decisions, or form opinions before one has all the pertinent facts. I know you found some suspicious things in her office, but don't rush to conclusions—talk to her first. I must apologize for rushing to conclusions earlier. I should have given you the benefit of the doubt.
rush to conclusions
to try to reach a conclusion too fast, probably with insufficient evidence; to jump to conclusions. I hope that you don't rush to any conclusions. I can explain this. I'm afraid you are rushing to conclusions when you speak of canceling the performance.