"And those who believe in what has been revealed to you", meaning: the Quran; "and what was revealed before you", meaning: the Torah, the Gospel, and the Psalms; they believe in them, but they do not act except according to what is in the Quran.
﴿وَالَّذِينَ يُؤْمِنُونَ بِمَا أُنْزِلَ إِلَيْكَ﴾ يَعْنِي: الْقُرْآن ﴿وَمَا أُنْزِلَ مِنْ قبلك﴾ يَعْنِي: التَّوْرَاة وَالْإِنْجِيل وَالزَّبُور؛ يصدقون بِهَا وَلا يعْملُونَ إِلَّا بِمَا فِي الْقُرْآن