Since official channels are closed, you will likely need to sideload the application. Here is the standard procedure:

To run the Facebook app on Nokia 5800 XpressMusic, the device must meet the following system requirements:

The Nokia 5800 XpressMusic was a flagship device from Nokia, designed to provide users with a rich multimedia experience. It came with a built-in music player, FM radio, and support for popular audio formats. The device also featured a 3.2-inch touchscreen display, 3.5G connectivity, and a 2-megapixel camera. The phone ran on the Symbian OS, which allowed users to install various applications, including games, productivity tools, and social media apps.

The original (later Nokia Store) was the only source for verified, Symbian-signed applications. Since that service was shuttered years ago, any modern site claiming a "verified download" for this specific model is likely hosting an unverified mirror.

If you absolutely want a native .sis app icon on your Nokia 5800’s home screen, there is one version that partially works. This is the closest to a “nokia 5800 xpressmusic facebook app free download verified” you will find.