[Then he called upon his Lord: that these are a criminal people] meaning: polytheists.
Muhammad said: Whoever recites "inna" (with a kasra), it is based on the meaning: He said: "Verily, these are...", and the fatha is permissible with the meaning: "Because these are..."
﴿فَدَعَا رَبَّهُ أَنَّ هَؤُلاءِ قَوْمٌ مجرمون﴾ مشركون.
قَالَ مُحَمَّد: من قَرَأَ (إِن) بالكَسْرِ فعلى معنى: قَالَ: إِن هَؤُلَاءِ، وَيجوز الْفَتْح بِمَعْنى: بِأَن هَؤُلَاءِ.