(102) باب دُعَاءِ النَّبِيِّ صلى الله عليه وسلم إِلَى الإِسْلاَمِ وَالنُّبُوَّةِ، وَأَنْ لاَ يَتَّخِذَ بَعْضُهُمْ بَعْضًا أَرْبَابًا مِنْ دُونِ اللَّهِ
Narrated Abu Huraira:
Allah 's Apostle said, " I have been ordered to fight with the people till they say, 'None has the right to be worshipped but Allah,' and whoever says, 'None has the right to be worshipped but Allah,' his life and property will be saved by me except for Islamic law, and his accounts will be with Allah, (either to punish him or to forgive him.)"
Reference: Sahih al-Bukhari 2946
In-book reference: Book 56, Hadith 158
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 52, Hadith 196