"And fight them until there is no more Fitnah (disbelief and polytheism, i.e., worshipping others besides Allah) and the religion (worship) will be all for Allah (Alone) (in the whole of the world)..." (V.8:39)

Sahih al-Bukhari · Book 65 · Hadith 4650

حَدَّثَنَا الْحَسَنُ بْنُ عَبْدِ الْعَزِيزِ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يَحْيَى، حَدَّثَنَا حَيْوَةُ، عَنْ بَكْرِ بْنِ عَمْرٍو، عَنْ بُكَيْرٍ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ ـ رضى الله عنهما ـ أَنَّ رَجُلاً، جَاءَهُ فَقَالَ يَا أَبَا عَبْدِ الرَّحْمَنِ، أَلاَ تَسْمَعُ مَا ذَكَرَ اللَّهُ فِي كِتَابِهِ ‏{‏وَإِنْ طَائِفَتَانِ مِنَ الْمُؤْمِنِينَ اقْتَتَلُو…

Narrated Ibn `Umar: That a man came to him (while two groups of Muslims were fighting) and said, "O Abu `Abdur Rahman! Don't you hear what Allah has mentioned in His Book: 'And if two groups of believers fight against e…