Responsa for Chullin 29:35

Q. A set aside two days as Yom-Kippur. [He would fast on the 10th and 11th of Tishri], If Yom-Kippur should fall on a Thursday [for A, therefore, Thursday and Friday], may he ask his neighbors to prepare meals for him on Friday for the Sabbath?
A. No, but he may partake of anything his neighbors and friends have prepared for themselves.
SOURCES: Pr. 76.