Jiub's Opus (Page 4) is a quest item in Skyrim: Dawnguard. It is needed to complete Impatience of a Saint
Location[edit]
To find Jiubs Opus page #4, go east around the castle, then climb two staircases, and find an alcove with the page inside near a chest.[1]
Visual Help/Screenshots[edit]
See how alcove looks like: