If you specifically need the older 280.x version for compatibility reasons, you can find the original (non-modded) files on reputable archive sites:

: Facebook's security systems can detect unofficial versions, which may result in your account being permanently disabled. Facebook Lite 280.0.0.9.119 (Android 4.0.3+) - APKMirror

: You can also download the installation file directly from the Facebook Lite website . Verified APK Archives

: The safest way to get the latest version of Facebook Lite is through the official store.