Hadith: I am not responsible for any Muslim who stays among the polytheists

عن جرير بن عبد الله قال: بعث رسول الله صلى الله عليه وسلم سَرِيَّةً إلى خَثْعَمٍ فاعٍتَصَمَ نَاسٌ منهم بالسجود، فَأَسْرَعَ فيهم القَتْلُ قال: فَبَلَغَ ذلك النبيَّ صلى الله عليه وسلم فَأَمَرَ لهم بنصف العَقْلِ وقال: «أنا بريء من كل مسلم يُقيم بين أَظْهُرِ المشركين». قالوا: يا رسول الله لم؟ قال: «لا تَرَاءَى نَارَاهُما».
[صحيح] - [رواه أبو داود والترمذي والنسائي]

Jarīr ibn ‘Abdullāh (may Allah be pleased with him) reported: 'The Messenger of Allah (may Allah's peace and blessings be upon him) sent a brigade to (the tribe of) Khath‘am. Some of their people sought protection by resorting to prostration but were hastily killed. When the Prophet (may Allah's peace and blessings be upon him) was informed of that, he ordered half the blood money to be paid for them, saying: "I am not responsible for any Muslim who stays among the polytheists." They asked: "Why, O Messenger of Allah?" He said: "Their fires should not be visible to one another.''
[Authentic hadith] - [Narrated by At-Termedhy - An-Nasaa’i - Narrated by Abu Daoud]

Explanation

The Prophet (may Allah's peace and blessings be upon him) sent an army brigade to a group from the tribe of Khath‘am who were disbelievers. So, some of them resorted to prostration to show that they were Muslim. However, the Muslims hastened to kill them, thinking that they were polytheists, and because they stayed among the polytheists. When it was later confirmed that they (who prostrated) had converted to Islam, the Prophet (may Allah's peace and blessings be upon him) made their blood money half of that of Muslims. He did not give them a full blood money because they were the reason behind their own killing. The Shariah forbids staying in the land of the disbelievers, such that Muslims should not meet the disbelievers or their fires cross. This means that they should not be close enough to see each other's fire. The purpose is for the Muslims to disassociate themselves from disbelief and its people.