Since that priest has already celebrated a Sunday Mass (on Sat night), no he does not need to either celebrate or attend another Mass on Sunday morning/day.
The old Canon Law I believe required a priest to celebrate at least one Mass every day even if by himself. Many priests had altars in the rectory or in the Convent next door, and if no Pariah Mass was celebrated they would celebrate Mass there. This is no longer required. At one time there were 400,000 priests (I forget exactly which old Almanac this came from) worldwide and if every priest (give or take a few) celebrated one Mass every day (except Good Friday and Holy Saturday). Divided by 24 hours that would be over 16,000 Masses for each hour, each day. Today I would guess that there are between 5,000 and 8,000 Masses being celebrated at any given time in the world.
My eyes bulged too, until I realized that “A” and “S” are next to each other on the keyboard, and to err is human!Pariah Mass?
