“Take a few days to think it over.”
You're planning on starting a business, and you've asked a friend to be your business partner. You know that this is a big decision. You say this to give your friend some time to decide.
Take a few days to think it over.
When you think someone needs time to do something, you tell them "take a minute" or "take a few days to ___". For example:
Take a few minutes to look it over and let me know if you have any questions.
When you "think ___ over", you think about it carefully and consider all of the possible good and bad points of it.
You use the phrase "think ___ over" when you're talking about an offer or a decision that you have to make. For example: