Word by Word Analysis

ثُمَّ لَمْ تَكُن فِتْنَتُهُمْ إِلَّآ أَن قَالُوا۟ وَٱللَّهِ رَبِّنَا مَا كُنَّا مُشْرِكِينَ 23

Then there will be no [excuse upon] examination except they will say, "By Allāh, our Lord, we were not those who associated."