I have always upgraded my installed homebrew packages whenever updates became available. Recently however, I ran into a situation where I did not want to upgrade a specific package while also upgrading the rest. Loved how incredibly easy Homebrew made this.

Upgrade all except pinned

Fetch the newest version of Homebrew and all formulae.

brew update

Now we can show formulae that have an updated version available. Pin the package that you do not want to upgrade. Once a package is pinned it will be ignored in upgrades. In order to make it eligible for upgrades again, unpin it. Note: You can run the brew pin/brew unpin commands at any time.

brew outdated
brew pin <package>
brew upgrade

Upgrade selected

brew update
brew outdated
brew upgrade <package>

Upgrade all

brew update
brew upgrade