The Calendar.
Jelly's Next Task is a written note found in Dishonored.
Transcript
Jelly,
You daft chaffer, here's another one for you.
"That old witch Granny Rags told me that you'll lose your taste for whiskey in the month of Wind. Then your eyes will go dim in the month of Seeds. And you'll draw your last breath in the month of Ice."
If you want your share you know what to do.
Location
It can be found in the Flooded District next to a safe. The note's clues indicate the combination (528) of the safe by using a nearby book on the different months.