If you have The Elder Scrolls V: Dawnguard add-on installed, you must have visited a location called Cairn of Souls. From the name it is clear that this is a world of captive spirits, and only owners of black souls get here. The portal leading to the dark Kingdom of the Dead is located in the castle of Volkihar. You can find it during the passage of the quest "In pursuit of an echo."
In total in Cairo you can go through four virtual puzzles. This article provides a description of the quest under the title "Impatient Saint."
Short description
After Dovakin enters Cairn of Souls, he may stumble upon the restless soul of Dunmer, whose name is Jiub. This soul will ask the protagonist to find a dozen pages from the first volume of his own autobiography, which were scattered from a height throughout the location.
Please note: if you add pages using console commands, the game will not be updated, which means that the pages of the opus Jiub will not become quest items.
Jiub Biography
The protagonist of the Impatient Saint quest is the one-eyed Dunmer Jiub. He first appeared in the third part of the legendary universe of The Elder Scrolls. Together with the main character, he arrived on the island of Vvardenfell. Little was known about him: most likely, he was a thief, but he did not belong to the Thieves Guild. According to rumors, Jiub died during the Oblivion crisis. However, the soul of Jiub is ready to tell Dovakin about his death 200 years later: he moved to Cyrodiil, where he was captured by the daedra who attacked the city. It was the princes of the daedra who sent him to Cairn of souls. In a conversation with the last Dragonborn, it turns out that Dunmer does not even realize that he was dead. Jiub will tell you the following: he believed that he was imprisoned in Tamriel and was awaiting his release all this time.
Where to look for pages?
The protagonist can find the first page in a niche where a lonely soul stands. To do this, go to the passage in the wall and go right along the structure. The second page will be found to the left of the entrance to the burial ground: here you will see the almost destroyed Wall of Words and a chest, behind which the desired item is located. Further, Dovakin should head west: before reaching the first wall, he will find a small enclosed nook in which the building is located. The third page is there. After that, head straight north from Jiuba Camp: there, Dovakin will find the fourth page. The small structure where it is located is attached to the wall of the burial ground. From this place, head straight east: you will find an altar on which there will be a quest item. Another page needed to complete the Impatient Saint quest is among the things that are scattered next to Jiuba Camp. Another landmark is the well of energy. If the protagonist leaves the entrance portal along the road leading to the wall, he will find on the right side a structure covered with bars. Look there - a sheet of Danmer opus there.
Then the Dragonborn will see a small turret, inside which he can find what he is looking for. Passing the first wall, Dovakin must go north. As soon as he sees a huge building, over which a stone of souls of very impressive sizes hangs, he should climb the roof. A chest is located right under the shower stone, behind which the page is hidden. The last quest item can be found next to the ghostly merchant - the page from the book lies directly on the barrel by his wagon.
Reward
As a reward for completing the Impatient Saint quest in Skyrim, Dovakin will receive a St. Jiub Medallion that upgrades armor and the only copy of the Composition of St. Jiub. It was his pages that the protagonist helped to find the Dunmer.