ذٰلِكَ بِأَنَّهُم شاقُّوا اللَّهَ وَرَسولَهُ ۖ وَمَن يُشاقِّ اللَّهَ فَإِنَّ اللَّهَ شَديدُ العِقابِ

That is because they opposed Allah and His Messenger. And whoever opposes Allah - then indeed, Allah is severe in penalty.