I was randomly perusing the Old Testament today and chanced upon this passage from the Second Book of Maccabees:
2 Maccabees 15: 37-39: “Since Nicanor’s doings ended in this way, with the city remaining in the possession of the Hebrews from that time on, I will bring my story to an end here too. If it is well written and to the point, that is what I wanted; if it is poorly done and mediocre, that is the best I could do. Just as it is unpleasant to drink wine by itself or just water, whereas wine mixed with water makes a delightful and pleasing drink, so a skillfully composed story delights the ears of those who read the work. Let this, then, be the end. “
I thought that it would make a good prayer for any writer to say upon finishing a work. You can replace “Nicanor’s doings ended in this way, with the city remaining in the possession of the Hebrews from that time on,” with something relevant to your novel or short story, but you get the idea.