In section 9 of S. Y. Agnon's short story "The Kerchief", the narrator / protagonist gives us the scene at the Shabbat lunch meal:
When I came back with Father from the small prayer room she was already seated at the table wearing her kerchief, and the table was prepared with wine and cakes, large and small, round and doubled over. Father entered, said, "A Sabbath of peace and blessing," put his tallit on the bed, sat down at the head of the table, said "The Lord is my shepherd, I shall not want," blessed the wine, tasted the cake, and began, "A Psalm of David: The earth is the Lord's and the fullness thereof."
The two psalms specified here are Psalm 23 and Psalm 24, respectively.
The first time I read this, it threw me, because as far as I was aware, those psalms aren't generally said at the lunch meal; Psalm 23 is traditionally said at the third meal, according to what I had learned (and practice).
I did some research, though, and discovered that there are people who say these specific psalms at lunch, but they're a rather small minority.
What's the point of specifying specifically which psalms were being said? Aside from it being slightly confusing for those of us for whom that's not our custom, how does it advance the story? What effect does including them have?