Surah Al-Anfal — Ayah 13 (8:13)
ذَٰلِكَ بِأَنَّهُمۡ شَآقُّواْ ٱللَّهَ وَرَسُولَهُۥۚ وَمَن يُشَاقِقِ ٱللَّهَ وَرَسُولَهُۥ فَإِنَّ ٱللَّهَ شَدِيدُ ٱلۡعِقَابِ ١٣
English translation (Saheeh International)
That is because they opposed Allāh and His Messenger. And whoever opposes Allāh and His Messenger - indeed, Allāh is severe in penalty.
Brief commentary
What happened to the disbelievers, when they were killed and their limbs were struck, was because they went against Allah and His Messenger. They did not follow what they were instructed to do, and did not stop doing what they were told not to do. Those who oppose Allah and His Messenger, Allah is firm with the punishment for them in this world, with death and capture, and in the Afterlife, with the fire of Hell.