Reference
ID 5894
Collector Muhammad al-Bukhari
Book Sahih Bukhari
Chapter Fighting for the Cause of Allah (Jihaad)
Reference (English Book) Vol. 4, Book 52, Hadith 287
Reference (Arabic Book) Book 56, Hadith 258
Hadith Type Atar
Matn (English)

Narrated `Amr bin Maimun: `Umar (after he was stabbed), instructed (his would-be-successor) saying, "I urge him (i.e. the new Caliph) to take care of those non-Muslims who are under the protection of Allah and His Apostle in that he should observe the convention agreed upon with them, and fight on their behalf (to secure their safety) and he should not over-tax them beyond their capability."

Matn (Arabic)

حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ حُصَيْنٍ، عَنْ عَمْرِو بْنِ مَيْمُونٍ، عَنْ عُمَرَ ـ رضى الله عنه ـ قَالَ وَأُوصِيهِ بِذِمَّةِ اللَّهِ وَذِمَّةِ رَسُولِهِ صلى الله عليه وسلم أَنْ يُوفَى لَهُمْ بِعَهْدِهِمْ، وَأَنْ يُقَاتَلَ مِنْ وَرَائِهِمْ، وَلاَ يُكَلَّفُوا إِلاَّ طَاقَتَهُمْ‏.‏