Narrated Abu Ma`bad:
(the slave of Ibn `Abbas) Allah's Messenger (ﷺ) said to Mu`adh when he sent him to Yemen, "You will go to the people of the Scripture. So, when you reach there, invite them to testify that none has the right to be worshipped but Allah, and that Muhammad is His Apostle. And if they obey you in that, tell them that Allah has enjoined on them five prayers in each day and night. And if they obey you in that tell them that Allah has made it obligatory on them to pay the Zakat which will be taken from the rich among them and given to the poor among them. If they obey you in that, then avoid taking the best of their possessions, and be afraid of the curse of an oppressed person because there is no screen between his invocation and Allah."
Narrated Ibn `Abbas:
Allah's Messenger (ﷺ) said to Mu`adh bin Jabal when he sent him to Yemen. "You will come to the people of Scripture, and when you reach them, invite them to testify that none has the right to be worshipped except Allah and that Muhammad is His Apostle. And if they obey you in that, then tell them that Allah has enjoined on them five prayers to be performed every day and night. And if they obey you in that, then tell them that Allah has enjoined on them Sadaqa (i.e. rak`at) to be taken from the rich amongst them and given to the poor amongst them. And if they obey you in that, then be cautious! Don't take their best properties (as Zakat) and be afraid of the curse of an oppressed person as there is no screen between his invocation and Allah.
It is reported on the authority of Ibn 'Abbas that Mu'adh said: The Messenger of Allah (ﷺ) sent me (as a governor of Yemen) and (at the time of departure) instructed me thus: You will soon find yourself in a community one among the people of the Book, so first call them to testify that there is no god but Allah, that I (Muhammad) am the messenger of Allah, and if they accept this, then tell them Allah has enjoined upon them five prayers during the day and the night and if they accept it, then tell them that Allah has made Zakat obligatory for them that it should be collected from the rich and distributed among the poor, and if they agree to it don't pick up (as a share of Zakat) the best of their wealths. Beware of the supplication of the oppressed for there is no barrier between him and Allah.