Horror mystery story that I read back in highschool (2015-17). The murdered child ghost(s) keep saying the prayer "If I die before I wake, pray the Lord my soul to take" it's also on the cover of the book. Spoilers

[Kasey]

The protagonist is male, I can't remember if they are young or old. They move to a new house with a dilapidated backyard. I think at the end of the book they find the bodies of the children either in there wall or floor of the basement. One of the children would also hide in a closet or something and say that prayer.