﴿ هَلْ يَنظُرُونَ إِلَّا ٱلسَّاعَةَ أَن تَأْتِيَهُم بَغْتَةًۭ وَهُمْ لَا يَشْعُرُونَ ﴾

“ARE THEY [who are lost in sin] but waiting for the Last Hour - [waiting] that it come upon them of a sudden, without their being aware [of its approach]?”

وَلِأُبَيِّنَ لَكُم بَعْضَ الَّذِي تَخْتَلِفُونَ فِيهِ (and to explain to you some of those matters in which you differ...43:63) Since Bana Isra'il were drowned in arrogance and obstinacy, they had tampered with the Divine laws. Sayyidna ` Isa (علیہ السلام) disclosed the reality of such distortions. The words 'some matters' are used because some other matters were purely of mundane nature. He might have not felt the need to deal with those differences. (Bayan-ul-Qur an).