﴿ ذَٰلِكَ بِأَنَّهُمْ شَآقُّوا۟ ٱللَّهَ وَرَسُولَهُۥ ۚ وَمَن يُشَاقِقِ ٱللَّهَ وَرَسُولَهُۥ فَإِنَّ ٱللَّهَ شَدِيدُ ٱلْعِقَابِ ﴾

“This, because they have cut themselves off from God and His Apostle: and as for him who cuts himself off from God and His Apostle - verily, God is severe in retribution.”

That chastisement befalling them is because they had contended with they had opposed God and His Messenger whoever contends with God and with His Messenger surely God is severe in retribution against him.