Question about Weinberg's GR book

Does anyone know why does Weinberg discards the fourth order term of the purely spatial components of the ricci tensor? It's the chapter 9 (post-newtonian approximation) of his GR book. It doesn't make sense to me because he includes the R_{00} term of fourth order but not R_{ij}. I'd attach an image but I can't. In my edition is the 216 page.