The lives of all Muslims are equal; they are one hand against the others. The covenant (given by even the) lowliest of them must be respected. Behold, a Muslim must not be killed for a disbeliever, nor must one who has been given a covenant be killed while his covenant is still in force. If anyone introduces an evil, he will be responsible for it. Whoever introduces an evil deed or shelters a perpetrator incurs the curse of Allah, His Angels, and all the people · Explained ḥadīths

عن قيس بن عباد، قال: انطلقت أنا والأشتر، إلى علي رضي الله عنه فقلنا: هل عَهِدَ إليك رسول الله صلى الله عليه وسلم شيئًا لم يَعْهَدْهُ إلى الناس عامة؟ قال: لا، إلا ما في كتابي هذا، قال مسدد: قال: فأخرج كتابًا، وقال أحمد: كتابا من قِرَابِ سيفه، فإذا فيه «المؤمنون تَكَافَأُ دماؤهم، وهم يد على من سِوَاهم، ويسعى بذِّمَّتِهِم أدناهم، ألا لا يُقتل مؤمن بكافر، ولا ذُو عَهْد في عهده، من أحدث حَدَثَاً فعلى نفسه، ومن أحدث حدثا، أو آوى مُحْدِثاً فعليه لعنة الله والملائكة والناس أجمعين».

Qays ibn ‘Abbād reported: Al-Ashtar and I went to ‘Ali (may Allah be pleased with him) and said to him: "Has the Messenger of Allah (may Allah's peace and blessings be upon him) given you anything exclusive that he did not give to the people in general?" He said: "No, except what is in this document of mine." Mūsaddad said: "He then took out a document." Ahmad said: "A document from the sheath of his sword." It stipulated that "the lives of all Muslims are equal; they are one hand against the others. The covenant (given by even the) lowliest of them must be respected. Behold, a Muslim must not be killed for a disbeliever, nor must one who has been given a covenant be killed while his covenant is still in force. If anyone introduces an evil, he will be responsible for it. Whoever introduces an evil deed or shelters a perpetrator incurs the curse of Allah, His Angels, and all the people."

An-Nasaa’i - Narrated by Abu Daoud - Narrated by AhmadGradeAuthentic hadith

Explanation

This Hadīth indicates that some of the Tābi‘īn asked ‘Ali (may Allah be pleased with him) a question similar to that asked by Abu Juhayfah (may Allah be pleased with him) on another occasion. He asked if the Messenger of Allah (may Allah's peace and blessings be upon him) had given ‘Ali any exclusive knowledge different from the Qur’an? ‘Ali (may Allah be pleased with him) answered in the negative, affirming that he had nothing but a sheet on which were some rulings which ‘Ali had written from the Messenger of Allah (may Allah's peace and blessings be upon him). These included the ruling that the lives of all Muslims are equal, such that a Muslim would be killed for killing any Muslim. However, a Muslim would not be killed for killing a disbeliever, for a disbeliever is not equal to a Muslim in the inviolability of their blood. Also, the covenant of any Muslim is to be respected, whether it is given by a junior or a senior person, by a man or a woman. So if a Muslim gives a covenant of protection to someone, even if the person who is to be protected is a disbeliever, the covenant must be honored. It is not permissible to kill anyone who enters the lands of Islam under a covenant, for his life has been protected by virtue of this covenant. Anyone who does an evil deed or hides or shelters the perpetrator incurs the curse of Allah, the Angels, and all people. This means that he shall be dismissed from the mercy of Allah, the Exalted.

Reference

سنن أبي داود - سليمان بن الأشعث السِّجِسْتاني تحقيق: محمد محيي الدين عبد الحميد: المكتبة العصرية، صيدا – بيروت. السنن الصغرى للنسائي - أحمد بن شعيب ، النسائي -تحقيق: عبد الفتاح أبو غدة-مكتب المطبوعات الإسلامية – حلب- الطبعة: الثانية، 1406 – 1986. مسند الإمام أحمد بن حنبل المحقق: شعيب الأرنؤوط - عادل مرشد، وآخرون إشراف: د عبد الله بن عبد المحسن التركي مؤسسة الرسالة الطبعة: الأولى، 1421 هـ - 2001 م. إرواء الغليل في تخريج أحاديث منار السبيل /محمد ناصر الدين الألباني - إشراف: زهير الشاويش-المكتب الإسلامي – بيروت-الطبعة: الثانية 1405 هـ - 1985م. ذخيرة العقبى في شرح المجتبى.المؤلف: محمد بن علي بن آدم بن موسى الإثيوبي الوَلَّوِي دار المعراج الدولية للنشر و دار آل بروم للنشر والتوزيع الطبعة: الأولى/ 1416 هـ - 1996 م. عمدة القاري شرح صحيح البخاري/بدر الدين العينى - دار إحياء التراث العربي – بيروت-بدون تاريخ. - تسهيل الإلمام بفقه الأحاديث من بلوغ المرام، تأليف: صالح بن فوزان بن عبد الله الفوزان، الطبعة: الأولى، 1427 هـ - 2006 م. فتح ذي الجلال والاكرام بشرح بلوغ المرام، للشيخ ابن عثيمين، المكتبة الإسلامية - الطبعة الأولى 1427. توضِيحُ الأحكَامِ مِن بُلوُغ المَرَام، للبسام. مكتَبة الأسدي، مكّة المكرّمة.الطبعة: الخامِسَة، 1423 هـ .

This ḥadīth at HadeethEnc.com