"You are going to a people who are People of the Scripture. Invite them to testify that none has the right to be worshipped but Allah and that l am His Messenger. If they obey you in this, then teach them that Allah, the Glorious One, has enjoined five prayers upon them in every day and night (in twenty-four hours), and if they obey you in this, then tell them that Allah has made it obligatory for them to pay Zakah upon their assets and it is to be taken from the wealthy among them and given to the poor among them." Related by Al-Bukhari