The Book of Distribution of Al-Fay'
Sunan an-Nasā'ī 4146
لاَ إِلَهَ إِلاَّ اللَّهُ وَأَنَّ مُحَمَّدًا رَسُولُ اللَّهِ وَفَارَقُوا الْمُشْرِكِينَ وَأَقَرُّوا بِالْخُمُسِ فِي غَنَائِمِهِمْ وَسَهْمِ النَّبِيِّ صلى الله عليه وسلم وَصَفِيِّهِ فَإِنَّهُمْ آمِنُونَ بِأَمَانِ اللَّهِ وَرَسُولِهِ
lā ilaha illā-Llāh wa-anna muḥammadan rasūlu-Llāh wafāraqūā al-mushrikīna wa-aqarrūā bi-l-khumusi fī ghanāʾimihim wasahmi an-nabiyyi ṣlā-Llāh ʿlyh wslm waṣafiyyihi fa-innahum āminūna biʾamāni-Llāh warasūlihi
Transliteration generated from the Arabic vowel marks
The full narration
It was narrated that Yazid bin Ash-Shikhkhir said:"While I was with Mutarrif in Al-Mirbad, a man came in carrying a piece of leather and said: 'This was written to me by the Messenger of Allah. Is there anyone among you who can read?' I said: 'I can read.' And it was (a letter) from Muhammad the Prophet to Banu Zuhair bin Uqaish, who had testified to Lailah illallah, and that Muhammad is the Messenger of Allah, and had left the idolaters, and had agreed to give the Khumus from their spoils of the Prophet, and wheatever he chose for himself, so they became safe and secure by the covenant of Allah and His Messenger
Source
Sunan an-Nasā'ī · 4146
- Abu Ghuddah: Sahih Isnaad
- Al-Albani: Sahih Isnaad
- Zubair Ali Zai: Sahih