the Book (Kitab) as a guide and criterion

۞ أَتَأْمُرُونَ ٱلنَّاسَ بِٱلْبِرِّ وَتَنسَوْنَ أَنفُسَكُمْ وَأَنتُمْ تَتْلُونَ ٱلْكِتَـٰبَ ۚ أَفَلَا تَعْقِلُونَ

Do you order righteousness of the people and forget yourselves while you recite the Scripture? Then will you not reason?