To jump to conclusions is to decide something without having all the facts.
- Please don’t jump to conclusions until you hear what I have to say.
- Before jumping to conclusions you must get your facts right.
- I incorrectly blamed him for breaking my window. I shouldn’t have jumped to conclusions.
- Why did you accuse him of stealing your purse? It wasn’t him. You shouldn’t jump to conclusions before getting your facts right.
Keep your fingers crossed
If you are keeping your fingers crossed, you are hoping for a good outcome for someone or something.
- I would like Alan to win the championship. I am keeping my fingers crossed for him.
- I don’t even have a one in ten chance of winning, but I am keeping my fingers crossed.
- I hope it doesn’t get worse. Let’s cross our fingers.
- I don’t think our team will win, but we better keep our fingers crossed. (= Let’s hope for the best.)