[jump] to (a|the) conclusion

to make a hasty or premature judgment or decision without sufficient evidence or information

Before hearing all the facts, she jumped to the conclusion that he was guilty.
The detective cautioned his team not to jump to conclusions during the investigation.
When problem-solving, it's best to consider all options and not jump to conclusions.
Instead of listening to the entire story, he jumped to a conclusion based on a single piece of information.
Her habit of jumping to conclusions often led to misunderstandings with her colleagues.