Tafsir of Surah Al-Anfaal 8:13
﴿ذَٰلِكَ بِأَنَّهُمْ شَاقُّوا اللَّهَ وَرَسُولَهُ وَمَن يُشَاقِقِ اللَّهَ وَرَسُولَهُ فَإِنَّ اللَّهَ شَدِيدُ الْعِقَابِ﴾
Translation of the meaning
That is because they opposed Allāh and His Messenger. And whoever opposes Allāh and His Messenger - indeed, Allāh is severe in penalty.
English Translation - Noor International Center — v1.1.2 · QuranEnc.comThe words of the two imams are given in their original Arabic, verbatim, with references.
Shaykh al-Islam Ibn Taymiyyah
فجعل إلقاء الرعب في قلوبهم والأمر بقتلهم لأجل مشاقتهم لله ورسوله فكل من شاق الله ورسوله يستوجب ذلك.«الصارم المسلول على شاتم الرسول» 1/28