Salaam Abdallah,

You need to enable the Extras-devel repository, mPrayerTime can be found there.

If you dont have Extras-devel you can enable it as follows:
1. Open the Application manager
2. Hit the title bar to display the application manager menu
3. Hit Application catalogs
4. Add a new catalog with the following details:

Catalog name: Maemo Extras-devel
Web address: http://repository.maemo.org/extras-devel
Distribution: fremantle
Components: free non-free