Friday has a shape to it, and children notice it long before anyone explains it.
This book sets out what makes Jumu'ah different — washing and dressing well, going early, the manners of sitting and listening while the khutbah is given, and the du'a made on that day. Useful preparation for a child attending the masjid for the first time, or for one who goes weekly without quite knowing why things are done the way they are.
