When Messenger of Allah ﷺ sent Muʿadh to Yemen, he said (to him), "YOU are going to people of a (Divine) Book. First of all invite them to worship Allah (alone) and when they come to know Allah, inform them that Allah has enjoined on them, five prayers in every day and night; and if they start offering these prayers, inform them that Allah has enjoined on them, the Zakat. And it is to be taken from the rich amongst them and given to the poor amongst them; and if they obey you in that, take Zakat from them and avoid (don't take) the best property of the people as Zakat." (Using translation from Bukhārī 1458)
أَنَّ رَسُولَ اللَّهِ ﷺ لَمَّا بَعَثَ مُعَاذًا إِلَى الْيَمَنِ قَالَ «إِنَّكَ تَقَدُمُ عَلَى قَوْمٍ مِنْ أَهْلِ الْكِتَابِ فَلْيَكُنْ أَوَّلَ مَا تَدْعُوهُمْ إِلَيْهِ عِبَادَةُ اللَّهِ فَإِذَا عَرَفُوا اللَّهَ فَأَخْبِرْهُمْ أَنَّ اللَّهَ فَرَضَ عَلَيْهِمْ خَمْسَ صَلَوَاتٍ فِي يَوْمِهِمْ وَلَيْلَتِهِمْ وَإِذَا فَعَلُوهَا فَأَخْبِرْهُمْ أَنَّ اللَّهَ فَرَضَ عَلَيْهِمْ زَكَاةً تُؤْخَذُ مِنْ أَمْوَالِهِمْ فَتُرَدُّ عَلَى فُقَرَائِهِمْ فَإِذَا أَطَاعُوا بِهَذَا فَخُذْ مِنْهُمْ وَتَوَقَّ كَرَائِمَ أَمْوَالِ النَّاسِ»