It was narrated from Ibn 'Abbas that the Prophet sent Mu'adh bin Jabal to Yemen and said:
"You are going to some people from among the people of the Book. Call them to bear witness that there is none worthy of worship except Allah and that I am the Messenger of Allah. If they obey you in that, then teach them that Allah has enjoined upon them five prayers every day and night. If they obey you in that, then teach them that Allah has enjoined upon them Sadaqah (Zakah) from their wealth, to be taken from their rich and given to their poor. If they obey you in that, then do not touch the most precious of their wealth, and fear the supplication of the one who has been wronged, for there is no barrier between it and Allah, the Mighty and Sublime."
أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ الْمُبَارَكِ، قَالَ حَدَّثَنَا وَكِيعٌ، قَالَ حَدَّثَنَا زَكَرِيَّا بْنُ إِسْحَاقَ، - وَكَانَ ثِقَةً - عَنْ يَحْيَى بْنِ عَبْدِ اللَّهِ بْنِ صَيْفِيٍّ، عَنْ أَبِي مَعْبَدٍ، عَنِ ابْنِ عَبَّاسٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم بَعَثَ مُعَاذَ بْنَ جَبَلٍ إِلَى الْيَمَنِ فَقَالَ ‏ "‏ إِنَّكَ تَأْتِي قَوْمًا أَهْلَ كِتَابٍ فَادْعُهُمْ إِلَى شَهَادَةِ أَنْ لاَ إِلَهَ إِلاَّ اللَّهُ وَأَنِّي رَسُولُ اللَّهِ فَإِنْ هُمْ أَطَاعُوكَ فَأَعْلِمْهُمْ أَنَّ اللَّهَ عَزَّ وَجَلَّ افْتَرَضَ عَلَيْهِمْ خَمْسَ صَلَوَاتٍ فِي كُلِّ يَوْمٍ وَلَيْلَةٍ فَإِنْ هُمْ أَطَاعُوكَ فَأَعْلِمْهُمْ أَنَّ اللَّهَ عَزَّ وَجَلَّ قَدِ افْتَرَضَ عَلَيْهِمْ صَدَقَةً فِي أَمْوَالِهِمْ تُؤْخَذُ مِنْ أَغْنِيَائِهِمْ فَتُوضَعُ فِي فُقَرَائِهِمْ فَإِنْ هُمْ أَطَاعُوكَ لِذَلِكَ فَإِيَّاكَ وَكَرَائِمَ أَمْوَالِهِمْ وَاتَّقِ دَعْوَةَ الْمَظْلُومِ فَإِنَّهَا لَيْسَ بَيْنَهَا وَبَيْنَ اللَّهِ عَزَّ وَجَلَّ حِجَابٌ ‏"‏ ‏.‏
GradeSahih (Darussalam)
Reference : Sunan an-Nasa'i 2522
In-book reference : Book 23, Hadith 0
English translation : Vol. 3, Book 23, Hadith 2523