Sahih Bukhari Volume 1, Book 8, Hadith 392

حَدَّثَنَا نُعَيْمٌ، قَالَ حَدَّثَنَا ابْنُ الْمُبَارَكِ، عَنْ حُمَيْدٍ الطَّوِيلِ، عَنْ أَنَسِ بْنِ مَالِكٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ أُمِرْتُ أَنْ أُقَاتِلَ النَّاسَ حَتَّى يَقُولُوا لاَ إِلَهَ إِلاَّ اللَّهُ‏.‏ فَإِذَا قَالُوهَا وَصَلَّوْا صَلاَتَنَا، وَاسْتَقْبَلُوا قِبْلَتَنَا، وَذَبَحُوا ذَبِيحَتَنَا، فَقَدْ حَرُمَتْ عَلَيْنَا دِمَاؤُهُمْ وَأَمْوَالُهُمْ إِلاَّ بِحَقِّهَا، وَحِسَابُهُمْ عَلَى اللَّهِ ‏"

Narrated By Anas bin Malik : Allah's Apostle said, "I have been ordered to fight the people till they say: 'None has the right to be worshipped but Allah.' And if they say so, pray like our prayers, face our Qibla and slaughter as we slaughter, then their blood and property will be sacred to us and we will not interfere with them except legally and their reckoning will be with Allah."