How to use Facebook without Messenger on Android / iOS

For some time, Facebook forces users of their mobile application to install Messenger if they want to read or send messages. This is certainly part of their growth strategy, but it has the effect of having two applications running in the background of the phone, which may lead to weakening the battery.

Facebook inviting to install Messenger (Android / iOS)

 
This is how you can override this constraint when Facebook will prompt you to:
1. Click Install (iOS) or "Get the application" (Android)
2. Start downloading and then cancel it after 2 to 3 seconds.
3. Return to the Facebook application. Messages should appear now.
4. Enjoy!