وَٱلَّذِىٓ أَوْحَيْنَآ إِلَيْكَ مِنَ ٱلْكِتَٰبِ هُوَ ٱلْحَقُّ مُصَدِّقًا لِّمَا بَيْنَ يَدَيْهِ
The same expression was treated in al-Aḥqāf at 46/12 and 46/30 — there it occurred both from the text itself and from the mouths of the jinn as an attaching to the chain. I rely on that treatment.
And the place of the verse within this sūra is worth recording: the next verse (32) will speak of the Book's being left as an inheritance. That is: first the Book's relation to the preceding link, then its handing on to the following one.
I record this as an observation about the word order: together the two verses hold the two ends of a chain — confirmation backwards, inheritance forwards.