وَالَّذِينَ يُمَسِّكُونَ بِالْكِتَابِ وَأَقَامُوا الصَّلَاةَ إِنَّا لَا نُضِيعُ أَجْرَ الْمُصْلِحِينَ
As for those who hold fast to the Book and maintain the prayer—indeed, We do not waste the reward of those who bring about reform.
Agha Ali Puya Commentary
Commentary on Quran 7:170
[Pooya/Ali Commentary 7:170] "Hold fast by the book" refers to the Quran and the Ahl ul Bayt of the Holy Prophet-see hadith al thaqalayn on page 6. Also refer to al Baqarah: 2 for kitab (the book).