إِنَّ هَٰذَا لَفِي الصُّحُفِ الْأُولَىٰ ۞ صُحُفِ إِبْرَاهِيمَ وَمُوسَىٰ
Indeed this is in the earlier scriptures, the scriptures of Abraham and Moses. (87:18–19)
Inna and the emphatic lām intensify the assertion. “The scriptures of Abraham and Moses” identifies what was first called “the earlier scriptures”; specification after a general expression strengthens clarity.
The demonstrative “this” is naturally understood with reference to the preceding teaching, not mechanically restricted to one isolated word. The closing lines situate that moral message within a longer continuity of revelation.