Everyone deals with the approach of death in their own way. Some look for God's forgiveness, others try to do right by their loved ones, others to set their wordly affairs in order.
During Pestilence quest, Henry will speak to a sick Vincent, who will request his help writing a will and delivering it to the Sasau Parish Priest, Father Fabian. Henry will only be able to acquiesce if he can read. Once the will is written, Vincent will also give Henry a silver ring.
Once in Sasau, Henry can either give the parish priest the ring as Vincent requested, in which case Fabian will take the will and reward you with 175 for your trouble, or he can ask where to find Vincent's disowned son Elijah, who spends his days at the Tavern on the Green. Speak to the innkeeper, who will tell Henry he is sitting at one of the tables outside.
Question the various villagers until you find Elijah, and inform him that his father is at death's door. At this point, you can either allow yourself to be bribed so that Elijah can destroy the will and inherit everything, or you can convince him to go home and make peace with his father.
After that, give the will