Poverty, Chastity and Obedience is another main quest in Kingdom Come: Deliverance. Henry needs to make preparations for infiltrating the Sasau Monastery. The plan is to substitute the noble who is supposed to enter the monastery. You have to get an entry writ.
Find Karl, the nobleman
You have to exit the church. Approach the closed door and pick up Key to Sasau church that lies on the ground. Go to Radzig in Rattay first before you start searching for Karl (he suggests you to arrest Pious instead of killing the man after you find him).
Karl can be found in the inn located south from the monastery. Enter the building. Karl should be in the main room and you can recognize him by the green shirt and the hat - the picture shows him. Change the time of a day if he isn't there and try again.
Get the Monastery entry writ
After a short conversation you learn that he can't speak with Henry in private because he is accompanied by a guardian. This problem can be solved in a few different ways. The most obvious one is to speak with guardian Manfred. You can:
Use impress option - he has 11 points in this category. You can convince him that you have an important message from Karl's father.
Use persuasion option - he has 9 points in this category. If you succeed, you will be able to play dice with him. This time you have to get 3,000 points but it doesn't matter whether you win or not. After that Manfred should drink and leave the table.
The goal of both of these actions is to separate Manfred from Karl (see the picture). Note - There is a possibility that you can run into a bug here - Manfred won't go anywhere. Wait a little bit longer for a waitress to appear or reload your game.
Speak with Karl again when he is alone about the Monastery entry writ. Karl also ask you to get Manfred's purse.
Manfred goes on the upper floor of the inn and rests in one of the beds. Sneak into his room (remember to remove all pieces of armor that make sound) and pickpocket the man (this is very risky). You can also suffocate him a little bit until he loses consciousness (a better idea). Take out Monastery entry writ and Manfred' purse from his inventory. You can give the second item to Karl (you can either give him everything or keep part of it for you).
The Monastery entry writ can also be acquired by skipping the meeting with Karl and Manfred at the inn's ground floor. Wait until night and sneak into the last room on the upper floor. The Monastery entry writ is in the chest presented in the picture above. Use a lockpick or find a key to it.
Enter the monastery
VERY IMPORTANT NOTE - Henry loses access to all of his items temporarily after entering the monastery. Unfortunately, the game has a serious error which causes weapons and elements of armor put into the monastery chest to be permanently lost or marked as stolen (this might happen, for instance, if Henry gets thrown out of the Monastery). The solution to that is to place all of your items into one of Henry's personal chests. You can rent a room in Sasau inn and move all your items into the chest on the floor (all chests share their content with each other) or you can go back to, e.g. one of your beds in Rattay.
Head to the Sasau Monastery and find Brother Porter. Show him the entry writ. During the conversation you can avoid problems by lying and using persuasion (Porter has 12 in that category) or you can rely on intimidation (Porter has 4 points) but this isn't required. You will also be asked if you can read. If Henry still does not have this skill, you should be interested in the side quest called Mightier than the Sword (the description of this quest can be found in the chapter about side quests in Uzhitz). As a reminder, you need to get to the scribe from the Uzhitz village and pay for basic reading lessons.
Confirm that you want to enter the monastery (the picture above). NOTE - You can't explore the world freely until you finish the next quest. Reach the chest with Henry's items and take out the monk's habit. The quest ends after the cut-scene that shows the moment of entering the monastery. After that you start two quests - A Needle in a Haystack main quest (find Pious) and In the Cloister (related to your stay in the monastery).